Generac Power Systems GP1800, GP3250, GP5000, GP5500, GP6500 Repair Manual

Diagnostic

®

RepaiR

Manual

GP Series Portable Generators

MODELS:

GP1800
GP3250
GP5000
GP5500
GP6500
GP7000
GP8000

PORTABLE GENERATORS

SAFETY

Throughout this publication, “DANGER!” and “CAUTION!” blocks are used to alert the mechanic to special
instructions concerning a particular service or operation that might be hazardous if performed incorrectly or
carelessly. PAY CLOSE ATTENTION TO THEM.

DANGER! UNDER THIS HEADING WILL BE FOUND SPECIAL INSTRUCTIONS WHICH, IF NOT COMPLIED

WITH, COULD RESULT IN PERSONAL INJURY OR DEATH.

*

CAUTION! Under this heading will be found special instructions which, if not complied with, could result

in damage to equipment and/or property.

*

These “Safety Alerts” alone cannot eliminate the hazards that they signal. Strict compliance with these special
instructions plus “common sense” are major accident prevention measures.

NOTICE TO USERS OF THIS MANUAL

This SERVICE MANUAL has been written and published by Generac to aid our dealers' mechanics and com­pany service personnel when servicing the products described herein.

It is assumed that these personnel are familiar with the servicing procedures for these products, or like or
similar products manufactured and marketed by Generac. That they have been trained in the recommended
servicing procedures for these products, including the use of common hand tools and any special Generac
tools or tools from other suppliers.

Generac could not possibly know of and advise the service trade of all conceivable procedures by which a
service might be performed and of the possible hazards and/or results of each method. We have not under­taken any such wide evaluation. Therefore, anyone who uses a procedure or tool not recommended by
Generac must first satisfy themselves that neither his nor the products safety will be endangered by the ser­vice procedure selected.

All information, illustrations and specifications in this manual are based on the latest product information
available at the time of publication.

When working on these products, remember that the electrical system and engine ignition system are capa­ble of violent and damaging short circuits or severe electrical shocks. If you intend to perform work where
electrical terminals could be grounded or touched, the battery cables should be disconnected at the battery.

Any time the intake or exhaust openings of the engine are exposed during service, they should be covered to
prevent accidental entry of foreign material. Entry of such materials will result in extensive damage when the
engine Is started.

During any maintenance procedure, replacement fasteners must have the same measurements and
strength as the fasteners that were removed. Metric bolts and nuts have numbers that indicate their strength.
Customary bolts use radial lines to indicate strength while most customary nuts do not have strength mark­ings. Mismatched or incorrect fasteners can cause damage, malfunction and possible injury.

Components on Generac recreational vehicle generators are designed and manufactured to comply with
Recreational Vehicle Industry Association (RVIA) Rules and Regulations to minimize the risk of fire or explo­sion. The use of replacement parts that are not in compliance with such Rules and Regulations could result
in a fire or explosion hazard. When servicing this equipment, it is extremely important that all components be
properly installed and tightened. If improperly installed and tightened, sparks could ignite fuel vapors from fuel
system leaks.

REPLACEMENT PARTS

Specifications .......................................................... 2

Part 1 – General Information .................................. 9

Section 1.1 – Generator Fundamentals ................ 10

Magnetism .......................................................10

Electromagnetic Fields.....................................10

Electromagnetic Induction................................10

A Simple AC Generator ...................................11

A More Sophisticated AC Generator ................11

Section 1.2 – Measuring Electricity ....................... 13

Meters ............................................................13

The VOM ..........................................................13

Measuring AC Voltage .....................................13

Measuring DC Voltage .....................................13

Measuring AC Frequency ................................13

Measuring Current ...........................................14

Measuring Resistance .....................................14

Electrical Units .................................................15

Ohm's Law .......................................................15

Section 1.3 – Brushless, Capacitor

Excitation System ............................ 16

Introduction ......................................................16

Stator Assembly ...............................................16

Rotor Assembly ................................................16

Circuit Breakers ...............................................16

Operation .........................................................17

Section 1.4 – Brushed Excitation System ............. 18

Introduction ......................................................18

Stator Assembly ...............................................18

Brush Holder and Brushes ...............................18

Rotor Residual Magnetism...............................18

Voltage Regulator ............................................18

Operation .........................................................18

Section 1.5 – Testing, Cleaning and Drying .......... 20

Insulation Resistance .......................................20

The Megohmmeter...........................................20

Stator Insulation Resistance Test .....................20

Cleaning the Generator ....................................21

Drying the Generator .......................................21

Part 2 – AC Generators ......................................... 21

Section 2.1 – Brushless Capacitor

Troubleshooting Flowcharts ............. 22

Section 2.2 – Brushed Excitation

Troubleshooting Flowcharts ............. 24

Section 2.3 – AC Diagnostic Tests ........................ 26

Introduction ......................................................26

Test 1 – Check No-Load Voltage

and Frequency ....................................26

Test 2 – Check Circuit Breaker.........................26

Test 3 – Check Continuity of

Receptacle Panel ................................26

Test 4 – Field Flash Alternator

(Configuration “A” Only) .......................27

Test 5 – Check Brushed Rotor Circuit ..............28

Test 6 – Check Capacitor .................................29

Test 7 – Test Brushless DPE Winding ..............30

Test 8 – Test Brushless Stator Windings ..........30

Test 9 – Test Brushed Stator Windings ............31

Test 10 – Check Load Voltage & Frequency ....31

Test 11 – Check Load Watts & Amperage .......31

Test 12 – Adjust Voltage Regulator ..................31

Part 3 – Engine Troubleshooting .......................... 33

Section 3.1 – 389/206/163cc Troubleshooting

Flowcharts ....................................... 34

Section 3.2 – 410cc Troubleshooting Flowcharts .. 37

Section 3.3 – Diagnostic Tests .............................. 42

Test 20 – Check 1.5 Amp Fuse ........................42

Test 21 – Check Battery & Cables ...................42

Test 22 – Check Voltage at

Starter Contactor (SC) ........................42

Test 23 – Check Start-Run-Stop Switch ..........42

Test 24 – Test OFF-ON Switch .........................43

Test 25 – Check Starter Motor .........................43

Test 25 – Check Ignition Spark ........................45

Test 26 – Check Spark Plugs ...........................46

Test 29 – Check Carburetion ...........................46

Test 30 – Choke Test ........................................47

Test 33 – Check Valve Adjustment ...................47

Test 36 – Check Engine / Cylinder Leak Down

Test / Compression Test ......................48

Test 38 – Check Flywheel ................................48

Test 39 – Remove Wire 18 / Shutdown Lead ...49
Test 40 – Check / Adjust Governor

(389cc Engine) ....................................49

Test 41 – Check / Adjust Governor

(410cc Engine) ....................................50

Test 45 – Check Oil Level Switch .....................51

Test 46 – Check Oil Pressure Switch ...............51

Test 49 – Test Recoil Function .........................52

Test 50 – Test Engine Function ........................52

Part 4 – Disassembly ............................................. 53

Section 4.1 – Major Disassembly .......................... 54

Part 5 – Electrical Data .......................................... 71

Electrical Schematic, GP1850 .............................. 72

Electrical Schematic, GP3250 .............................. 73

Electrical Schematic, GP5000/5500/GP6500 ....... 74

Wiring Diagram, GP5000/5500/GP6500 ............... 75

Electrical Schematic, GP7000E/GP8000E ........... 76

Wiring Diagram, GP7000E/GP8000E ................... 77

Electrical Formulas ............................................... 78

Page 1

SPECIFICATIONS – GP1800

AH

M

Outlets

A

Circuit Breakers

M

Other Features

H

(2) 5-20R 120V

(1) 20A

On/Off Switch

Product Series GP1800

A/C Rated Output Watts: 1800

A/C Maximum Output Watts: 2050

A/C Voltage 120VAC

A/C Frequency 60 Hz

Rated 120 VAC Amperage 7.5

Max 120 VAC Amperage 8.5

Engine Displacement 163cc

Engine Type OHV

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Splash Sump

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method Manual

Battery n/a

Battery Size n/a

Low Oil Shutdown Method Low Level

Start Switch Type On/Off Toggle

Switch Location Control Panel

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 4

Fuel Tank Capacity (Liters) 15.14

Run Time at 50% (Hours) 14

Cord Set No

Handle Style Folding

Wheel type n/a

Length (L) 23.5

Width (W) 17

Height (H) 17.5

Extended Length (EL) 23.5

Unit Weight (lbs) 79

Spark Plug Type NGK BPR4ES

or Champion
RN14YC

Spark Plug Gap 0.028"-0.031"

(0.7-0.8mm)

Oil Capacity 0.634 quart

(0.6 liter)

Page 2

H

A

M

Product Series GP3250

A/C Rated Output Watts: 3250

A/C Maximum Output Watts: 3750

A/C Voltage 120VAC

A/C Frequency 60 Hz

Rated 120 VAC Amperage 13.5

Max 120 VAC Amperage 15.6

Engine Displacement 206cc

Engine Type OHV

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Splash Sump

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method Manual

Battery n/a

Battery Size n/a

Low Oil Shutdown Method Low Level

Start Switch Type On/Off Toggle

Switch Location Control Panel

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 4

Fuel Tank Capacity (Liters) 15.14

Run Time at 50% (Hours) 13.5

Cord Set No

Handle Style Folding

Wheel type 7.0" Solid Wheels

Length (L) 25.5

Width (W) 21

Height (H) 19

Extended Length (EL) 39.5

Unit Weight (lbs) 91

Spark Plug Type NGK BPR4ES

or Champion
RN14YC

Spark Plug Gap 0.028"-0.031"

(0.7-0.8mm)

Oil Capacity 0.634 quart

(0.6 liter)

SPECIFICATIONS – GP3250

Outlets

A

Circuit Breakers

M

Other Features

H

(4) 5-20R 120V

(2) 20A

On/Off Switch

Page 3

SPECIFICATIONS – GP5000

H

B

N

M

A

Receptacles

A

B

Circuit Breakers

M

N

Other Features

H

(4) 5-20R 120V

L14-30R Twist-Lock 120/240V

(2) 20A

(2) 25A

Hour Meter with

Maintenance Reset

Product Series GP5000

A/C Rated Output Watts: 5000

A/C Maximum Output Watts: 6250

A/C Voltage 120/240VAC

A/C Frequency 60 Hz

Rated 120/240 VAC Amperage 20.8

Max 120/240 VAC Amperage 26.0

Engine Displacement 389cc

Engine Type OHV

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Splash Sump

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method Manual

Battery n/a

Battery Size n/a

Low Oil Shutdown Method Low Level

Start Switch Type 3-Position

Switch Location On Engine

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 6.6

Fuel Tank Capacity (Liters) 24.981

Run Time at 50% (Hours) 10

Cord Set No

Handle Style Folding Interlocked

Wheel type 9.5" Solid Wheels

Length (L) 33.5

Width (W) 26.5

Height (H) 27.5

Extended Length (EL) 47

Unit Weight (lbs) 167

Spark Plug Type NHSP F7RTC or

Champion RN9YC

Spark Plug Gap 0.028"-0.031"

(0.7-0.8mm)

Oil Capacity 1.16 quart

(1.1 liter)

Page 4

SPECIFICATIONS – GP5500

H

B

N

M

A

Product Series GP5500

A/C Rated Output Watts: 5000

A/C Maximum Output Watts: 6875

A/C Voltage 120/240VAC

A/C Frequency 60 Hz

Rated 120/240 VAC Amperage 22.9

Max 120/240 VAC Amperage 28.6

Engine Displacement 389cc

Engine Type OHV

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Splash Sump

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method Manual

Battery n/a

Battery Size n/a

Low Oil Shutdown Method Low Level

Start Switch Type 3-Position

Switch Location On Engine

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 6.6

Fuel Tank Capacity (Liters) 24.98

Run Time at 50% (Hours) 10

Cord Set No

Handle Style Folding Interlocked

Wheel type 9.5" Solid Wheels

Length (L) 33.5

Width (W) 26.5

Height (H) 27.5

Extended Length (EL) 47

Unit Weight (lbs) 167

Spark Plug Type NHSP F7RTC or

Champion RN9YC

Spark Plug Gap 0.028"-0.031"

(0.7-0.8mm)

Oil Capacity 1.16 quart

(1.1 liter)

Receptacles

A

B

Circuit Breakers

M

N

Other Features

H

L14-30R Twist-Lock 120/240V

(4) 5-20R 120V

(2) 20A

(2) 25A

Hour Meter with

Maintenance Reset

Page 5

SPECIFICATIONS – GP6500

H

B

N

M

A

Outlets

A

B

Circuit Breakers

M

N

Other Features

H

Hour Meter with Maintenance Reset

(4) 5-20R 120V

L14-30R Twist-Lock 120/240V

(2) 20A

(2) 30A

Product Series GP6500

A/C Rated Output Watts: 6500

A/C Maximum Output Watts: 8000

A/C Voltage 120/240VAC

A/C Frequency 60 Hz

Rated 120/240 VAC Amperage 27.1

Max 120/240 VAC Amperage 33.3

Engine Displacement 389cc

Engine Type OHV

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Splash Sump

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method Manual

Battery n/a

Battery Size n/a

Low Oil Shutdown Method Low Level

Start Switch Type 3-Position

Switch Location On Engine

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 6.6

Fuel Tank Capacity (Liters) 24.98

Run Time at 50% (Hours) 9

Cord Set No

Handle Style Folding Interlocked

Wheel type 9.5" Solid Wheels

Length (L) 33.5

Width (W) 26.5

Height (H) 27.5

Extended Length (EL) 47

Unit Weight (lbs) 172

Spark Plug Type NHSP F7RTC or

Champion RN9YC

Spark Plug Gap 0.028"-0.031"

(0.7-0.8mm)

Oil Capacity 1.16 quart

(1.1 liter)

Page 6

Product Series GP7000

H

B

N

M

A

A/C Rated Output Watts: 7000

A/C Maximum Output Watts: 8750

A/C Voltage 120/240VAC

A/C Frequency 60 Hz

Rated 120/240 VAC Amperage 29.2

Max 120/240 VAC Amperage 36.5

Engine Displacement 410cc

Engine Type OHVI

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Full Pressure

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method GP7000 Manual

Starting Method GP7000E Manual or Electric

Battery Size (if equipped) 12VDC 10 Ahr

Low Oil Shutdown Method Low Pressure

Start Switch Type 3-Position

Switch Location On Engine

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 8

Fuel Tank Capacity (Liters) 30.28

Run Time at 50% (Hours) 11

Cord Set No

Handle Style Folding Interlocked

Wheel type 9.5" Solid Wheels

Spark Plug Type Champion RC14YC

Spark Plug Gap 0.030" (0.76mm)

Oil Capacity 1.5 quart w/filter

SPECIFICATIONS – GP7000/GP7000E

Outlets

A

B

Circuit Breakers

M

N

Other Features

H

Hour Meter with Maintenance Reset

(4) 5-20R 120V

L14-30R Twist-Lock 120/240V

(2) 20A

(2) 30A

Page 7

H

B

N

M

A

SPECIFICATIONS – GP8000/GP8000E

Outlets

A

B

Circuit Breakers

M

N

Other Features

H

Hour Meter with Maintenance Reset

(4) 5-20R 120V

L14-30R Twist-Lock 120/240V

(2) 20A

(2) 30A

Product Series GP8000/GP8000E

A/C Rated Output Watts: 8000

A/C Maximum Output Watts: 10000

A/C Voltage 120/240VAC

A/C Frequency 60 Hz

Rated 120/240 VAC Amperage 33.3

Max 120/240 VAC Amperage 41.7

Engine Displacement 410cc

Engine Type OHVI

Engine RPM 3600

Recommended Oil 5W30

Lubrication Method Full Pressure

Choke Type Manual Lever

Fuel Shut Off Manual Lever

Idle Control Full Speed

Starting Method GP8000 Manual

Starting Method GP8000E Manual or Electric

Battery Size (if equipped) 12VDC 10 Ahr

Low Oil Shutdown Method Low Pressure

Start Switch Type 3-Position

Switch Location On Engine

Single-Point Lifting Eye N/A

Fuel Gauge Built-In

Fuel Tank Capacity (Gal) 8

Fuel Tank Capacity (Liters) 30.28

Run Time at 50% (Hours) 8

Cord Set No

Handle Style Folding Interlocked

Wheel type 9.5" Solid Wheels

Spark Plug Type Champion RC14YC

Spark Plug Gap 0.030" (0.76mm)

Oil Capacity 1.5 quart w/filter

Page 8

PART 1

GENERAL

INFORMATION

GP Series Portable Generators

TABLE OF CONTENTS

PART TITLE PAGE

1.1 Generator Fundamentals 10

1.2 Measuring Electricity 13

1.3 Brushless, Capacitor Excitation
System

1.4 Brushed Excitation System 18

1.5 Testing, Cleaning and Drying 20

16

Part 1 – General Information .................................. 9

Section 1.1 – Generator Fundamentals ................ 10

Magnetism .......................................................10

Electromagnetic Fields.....................................10

Electromagnetic Induction................................10

A Simple AC Generator ...................................11

A More Sophisticated AC Generator ................11

Section 1.2 – Measuring Electricity ....................... 13

Meters ............................................................13

The VOM ..........................................................13

Measuring AC Voltage .....................................13

Measuring DC Voltage .....................................13

Measuring AC Frequency ................................13

Measuring Current ...........................................14

Measuring Resistance .....................................14

Electrical Units .................................................15

Ohm's Law .......................................................15

Section 1.3 – Brushless, Capacitor

Excitation System ............................ 16

Introduction ......................................................16

Stator Assembly ...............................................16

Rotor Assembly ................................................16

Circuit Breakers ...............................................16

Operation .........................................................17

Section 1.4 – Brushed Excitation System ............. 18

Introduction ......................................................18

Stator Assembly ...............................................18

Brush Holder and Brushes ...............................18

Rotor Residual Magnetism...............................18

Voltage Regulator ............................................18

Operation .........................................................18

Section 1.5 – Testing, Cleaning and Drying .......... 20

Insulation Resistance .......................................20

The Megohmmeter...........................................20

Stator Insulation Resistance Test .....................20

Cleaning the Generator ....................................21

Drying the Generator .......................................21

Page 9

SECTION 1.1

GENERATOR FUNDAMENTALS

PART 1

GENERAL INFORMATION

MAGNETISM

Magnetism can be used to produce electricity and
electricity can be used to produce magnetism.

Much about magnetism cannot be explained by our
present knowledge. However, there are certain pat­terns of behavior that are known. Application of these
behavior patterns has led to the development of gen­erators, motors and numerous other devices that uti­lize magnetism to produce and use electrical energy.

See Figure 1. The space surrounding a magnet is per­meated by magnetic lines of force called “flux”. These
lines of force are concentrated at the magnet's north
and south poles. They are directed away from the
magnet at its north pole, travel in a loop and re-enter
the magnet at its south pole. The lines of force form
definite patterns which vary in intensity depending on
the strength of the magnet. The lines of force never
cross one another. The area surrounding a magnet in
which its lines of force are effective is called a “mag­netic field”.

Like poles of a magnet repel each other, while unlike
poles attract each other.

NOTE: The “right hand rule” is based on the “cur­rent flow” theory which assumes that current
flows from positive to negative. This is opposite
the “electron” theory, which states that current
flows from negative to positive.

Figure 2. The Right Hand Rule

ELECTROMAGNETIC INDUCTION

Figure 1. Magnetic Lines of Force

ELECTROMAGNETIC FIELDS

All conductors through which an electric current is
flowing have a magnetic field surrounding them. This
field is always at right angles to the conductor. If a
compass is placed near the conductor, the compass
needle will move to a right angle with the conductor.
The following rules apply:

• Thegreater thecurrent flowthrough theconductor,

the stronger the magnetic field around the conductor.

• The increase inthe number of linesof force is

directly proportional to the increase in current flow
and the field is distributed along the full length of
the conductor.

• Thedirectionofthelinesofforcearoundaconduc­tor can be determined by what is called the “right
hand rule”. To apply this rule, place your right hand
around the conductor with the thumb pointing in
the direction of current flow. The fingers will then be
pointing in the direction of the lines of force.

An electromotive force (EMF) or voltage can be pro­duced in a conductor by moving the conductor so that
it cuts across the lines of force of a magnetic field.

Similarly, if the magnetic lines of force are moved so
that they cut across a conductor, an EMF (voltage)
will be produced in the conductor. This is the basic
principal of the revolving field generator.

Figure 3, below, illustrates a simple revolving field
generator. The permanent magnet (Rotor) is rotated
so that its lines of magnetic force cut across a coil of
wires called a Stator. A voltage is then induced into
the Stator windings. If the Stator circuit is completed
by connecting a load (such as a light bulb), current
will flow in the circuit and the bulb will light.

Figure 3. A Simple Revolving Field Generator

Page 10

GENERAL INFORMATION

S

TATOR

ROT

OR

MAGNETIC FIEL

D

CURRENT

VOLTAGE

ONE CYCLE

0

180

360

(+)

(-)

STATOR

ROTOR

GENERATOR

120 VAC

120 VAC

+

-

AC OUTPUT

STATOR

240 VAC

CAPACITOR

STATOR

BRUSHES

120 V

120 V

+

-

SLIP
RINGS

AC OUTPUTDC CURRENT

STATOR

240 V

PART 1

SECTION 1.1

GENERATOR FUNDAMENTALS

A SIMPLE AC GENERATOR

Figure 4 shows a very simple AC Generator. The gen­erator consists of a rotating magnetic field called a
ROTOR and a stationary coil of wire called a STATOR.
The ROTOR is a permanent magnet which consists of
a SOUTH magnetic pole and a NORTH magnetic pole.

As the MOTOR turns, its magnetic field cuts across
the stationary STATOR. A voltage is induced Into
the STATOR windings. When the magnet's NORTH
pole passes the STATOR, current flows in one direc­tion. Current flows in the opposite direction when the
magnet's SOUTH pole passes the STATOR. This con­stant reversal of current flow results in an alternating
current (AC) waveform that can be diagrammed as
shown in Figure 5.

The ROTOR may be a 2-pole type having a single
NORTH and a single SOUTH magnetic pole. Some
ROTORS are 4-pole type with two SOUTH and two
NORTH magnetic poles. The following apply:

1. The 2-pole ROTOR must be turned at 3600 rpm to pro­duce an AC frequency of 60 Hertz, or at 3000 rpm to
deliver an AC frequency of 50 Hertz.

2. The 4-pole ROTOR must operate at 1800 rpm to deliver
a 60 Hertz AC frequency or at 1500 rpm to deliver a 50
Hertz AC frequency.

A MORE SOPHISTICATED AC GENERATOR

Figure 6 and 7 show two methods of creating alternat­ing current that are implemented on GP Series por­table generator product.

Figure 6 shows a consistent voltage being induced to
the rotor from a capacitor which is installed in series
with the DPE winding. As a result a regulated voltage
is induced into the STATOR.

Figure 4. A Simple AC Generator

Figure 5. Alternating Current Sine Wave

Figure 6. Capacitive Discharge

Figure 7 shows a regulated direct current being deliv­ered into the ROTOR windings via carbon BRUSHES
AND SLIP RINGS. This results in the creation of
a regulated magnetic field around the ROTOR. As
a result, a regulated voltage is induced into the
STATOR. Regulated current delivered to the ROTOR
is called “EXCITATION” current.

Figure 7. Direct Excitation

Page 11

SECTION 1.1

CAPACITOR

STATOR

EXCITATION

WINDING

STATOR
POWER

WINDING

STATOR

POWER

WINDING

MAGNETIC

FIELD

MAGNETIC

FIELD

MLB = MAIN LINE
CIRCUIT BREAKER

ROTOR

TO LOAD

MLB

ENGINE ­DIRECT
DRIVE

AUTOMATIC

VOLTAGE

REGULATOR

+-

STATOR

EXCITATION

WINDING

STATOR
POWER

WINDING

STATOR
POWER

WINDING

MAGNETIC

FIELD

MAGNETIC

FIELD

SENSING

MLB = MAIN LINE
CIRCUIT BREAKER

ROTOR

TO LOAD

MLB

ENGINE ­DIRECT
DRIVE

120 VAC 120 VAC

240 VAC

120 VAC 120 VAC

240 VAC

A B

CAPACITIVE DISCHARGE DIRECT EXCITATION

GENERATOR FUNDAMENTALS

PART 1

GENERAL INFORMATION

Figure 8. Generator Operating Diagram

The revolving magnetic field is driven by the engine
at constant speed. This constant speed is maintained
by a mechanical engine governor. Units with a 2-pole
rotor require an operation speed of 3600 rpm to deliv­er a 60 Hertz AC output.

Generator operation may be described briefly as follows.

1. Some “residual” magnetism is normally present in the
Rotor, which is sufficient to induce approximately 1 to 2
Volts AC in to the Stator’s AC Power Windings and DPE
winding.

2. See Figure 8.

A. Dur ing startup, the “residual” voltage that

is induced into the DPE winding will initially
charge the capacitor to a greater potential.
When the capacitor is discharged the voltage
is in turn induced back into the Rotor which will
exponen tially raise the voltage to 120/240.

B. During startup, the “residual” voltage that is

induced into the DPE winding will turn on the
voltage regulator allowing DC excitation current
to be delivered to the rotor and raise the voltage
to 120/240.

Page 12

GENERAL INFORMATION

PART 1

SECTION 1.2

MEASURING ELECTRICITY

METERS

Devices used to measure electrical properties are called
meters. Meters are available that allow one to measure
(a) AC voltage, (b) DC voltage, (c) AC frequency, and
(d) resistance in ohms. The following apply:

• TomeasureACvoltage,useanACvoltmeter.

• TomeasureDCvoltage,useaDCvoltmeter.

• UseafrequencymetertomeasureACfrequencyin

“Hertz” or “cycles per second”.

• Use an ohmmeter to read circuit resistance, in

“Ohms”.

THE VOM

A meter that will permit both voltage and resistance to
be read is the “volt-ohm-milliammeter” or “VOM”.

Some VOMs are of the “analog” type (not shown).
These meters display the value being measured by
physically deflecting a needle across a graduated
scale. The scale used must be interpreted by the user.

“Digital” VOMs (Figure 1) are also available and are
generally very accurate. Digital meters display the
measured values directly by converting the values to
numbers.

NOTE: Standard AC volt me te rs react to the
AVERAGE value of alternating current. When work­ing with AC, the effective value is used. For that
reason a different scale is used on an AC voltme­ter. The scale is marked with the effective or “rms”
value even though the meter actually reacts to the
average value. That is why the AC voltmeter will
give an incorrect reading if used to measure direct
current (DC).

MEASURING AC VOLTAGE

An accurate AC voltmeter or a VOM may be used to
read the generator's AC output voltage. The following
apply:

1. Always read the generator's AC output voltage only at
the unit's rated operating speed and AC frequency.

2. The generator's Voltage Regulator can be adjusted for
correct output voltage only while the unit is operating at
its correct rated speed and frequency.

3. Only an AC voltmeter may be used to measure AC
voltage. DO NOT USE A DC VOLTMETER FOR THIS
PURPOSE.

DANGER! GENERATORS PRODUCE HIGH

AND DANGEROUS VOLTAGES. CONTACT

*

WITH HIGH VOLTAGE TERMINALS WILL
RESULT IN DANGEROUS AND POSSIBLY
LETHAL ELECTRICAL SHOCK.

MEASURING DC VOLTAGE

A DC voltmeter or a VOM may be used to measure
DC voltages. Always observe the following rules:

1. Always observe correct DC polarity.

a. Some VOM's may be equipped with a polar-

ity switch.

b. On meters that do not have a polarity switch,

DC polarity must be reversed by reversing
the test leads.

2. Before reading a DC voltage, always set the meter to a
higher voltage scale than the anticipated reading. If in
doubt, start at the highest scale and adjust the scale
downward until correct readings are obtained.

Figure 1. Digital VOM

3. The design of some meters is based on the “current
flow” theory while others are based on the “electron flow”
theory.

a. The “current flow” theory assumes that direct

current flows from the positive (+) to the
negative (-).

b. The “electron flow” theory assumes that cur-

rent flows from negative (-) to positive (+).

NOTE: When testing generators, the “current flow”
theory is applied. That is, current is assumed to
flow from positive (+) to negative (-).

MEASURING AC FREQUENCY

The generator's AC output frequency is proportional to
Rotor speed. Generators equipped with a 2-pole Rotor
must operate at 3600 rpm to supply a frequency of 60
Hertz. Units with 4-pole Rotor must run at 1800 rpm to
deliver 60 Hertz.

Page 13

SECTION 1.2

1.00 A

BATTERY

+-

RELAY

MEASURING ELECTRICITY

PART 1

GENERAL INFORMATION

Correct engine and Rotor speed is maintained by an
engine speed governor. For models rated 60 Hertz,
the governor is generally set to maintain a no-load fre­quency of about 62 Hertz with a corresponding output
voltage of about 124 volts AC line-to-neutral. Engine
speed and frequency at no-load are set slightly high
to prevent excessive rpm and frequency droop under
heavy electrical loading.

MEASURING CURRENT

CLAMP-ON:
To read the current flow, in AMPERES, a clamp-on

ammeter may be used. This type of meter indicates
current flow through a conductor by measuring the
strength of the magnetic field around that conductor.
The meter consists essentially of a current transform­er with a split core and a rectifier type instrument con­nected to the secondary. The primary of the current
transformer is the conductor through which the current
to be measured flows. The split core allows the instru­ment to be clamped around the conductor without
disconnecting it.

Current flowing through a conductor may be measured
safely and easily. A line-splitter can be used to measure
current in a cord without separating the conductors.

NOTE: If the physical size of the conductor or amme­ter capacity does not permit all lines to be measured
simultaneously, measure current flow in each indi­vidual line. Then, add the individual readings.

IN-LINE:
Alternatively, to read the current flow in AMPERES, an

in-line ammeter may be used. Most Digital Volt Ohm
Meters (VOM) will have the capability to measure
amperes.

This usually requires the positive meter test lead to be
connected to the correct amperes plug, and the meter
to be set to the amperes position. Once the meter is
properly set up to measure amperes the circuit being
measured must be physically broken. The meter will
be in-line or in series with the component being mea­sured.

In Figure 4 the control wire to a relay has been
removed. The meter is used to connect and supply
voltage to the relay to energize it and measure the
amperes going to it.

Figure 2. Clamp-On Ammeter

Figure 3. A Line-Splitter

Page 14

Figure 4. A VOM as an In-line meter

MEASURING RESISTANCE

The volt-ohm-milliammeter may be used to measure
the resistance in a circuit. Resistance values can be
very valuable when testing coils or windings, such as
the Stator and Rotor windings.

When testing Stator windings, keep in mind that the
resistance of these windings is very low. Some meters
are not capable of reading such a low resistance and
will simply read CONTINUITY.

If proper procedures are used, the following conditions
can be detected using a VOM:

• A“short-to-ground”condition inanyStatoror Rotor

winding.

•

Shorting together of any two parallel Stator windings.

•

Shorting together of any two isolated Stator windings.

• AnopenconditioninanyStatororRotorwinding.

GENERAL INFORMATION

-

+

AMPERE - Unit measuring rate of

current flow (number of electrons
past a given point)

OHM - Unit measuring resistance

or opposition to flow

VOLT - Unit measuring force or

difference in potential
causing current flow

Conductor of a
Circuit

VOLTS

(E)

AMPS

(I)

OHMS

(R)

PART 1

SECTION 1.2

MEASURING ELECTRICITY

Component testing may require a specific resis­tance value or a test for INFINITY or CONTINUITY.
Infinity is an OPEN condition between two electrical
points, which would read as no resistance on a VOM.
Continuity is a CLOSED condition between two electri­cal points, which would be indicated as very low resis­tance or “ZERO” on a VOM.

ELECTRICAL UNITS

AMPERE:
The rate of electron flow in a circuit is represented

by the AMPERE. The ampere is the number of elec­trons flowing past a given point at a given time. One
AMPERE is equal to just slightly more than six thou­sand million billion electrons per second (6.25 x 1018).

With alternating current (AC), the electrons flow first in
one direction, then reverse and move in the opposite
direction. They will repeat this cycle at regular inter­vals. A wave diagram, called a “sine wave” shows that
current goes from zero to maximum positive value,
then reverses and goes from zero to maximum nega­tive value. Two reversals of current flow is called a
cycle. The number of cycles per second is called fre­quency and is usually stated in “Hertz”.

VOLT :
The VOLT is the unit used to measure electrical

PRESSURE, or the difference in electrical potential
that causes electrons to flow. Very few electrons will
flow when voltage is weak. More electrons will flow as
voltage becomes stronger. VOLTAGE may be consid­ered to be a state of unbalance and current flow as
an attempt to regain balance. One volt is the amount
of EMF that will cause a current of 1 ampere to flow
through 1 ohm of resistance.

OHM:
The OHM is the unit of RESISTANCE. In every circuit

there is a natural resistance or opposition to the flow
of electrons. When an EMF is applied to a complete
circuit, the electrons are forced to flow in a single
direction rather than their free or orbiting pattern. The
resistance of a conductor depends on (a) its physical
makeup, (b) its cross-sectional area, (c) its length, and
(d) its temperature. As the conductor's temperature
increases, its resistance increases in direct proportion.
One (1) ohm of resistance will permit one (1) ampere
of current to flow when one (1) volt of electromotive
force (EMF) is applied.

OHM'S LAW

A definite and exact relationship exists between VOLTS,
OHMS and AMPERES. The value of one can be calcu­lated when the value of the other two are known. Ohm's
Law states that in any circuit the current will increase
when voltage increases but resistance remains the
same, and current will decrease when resistance
Increases and voltage remains the same.

Figure 5. Electrical Units

Figure 6. Ohm's Law

If AMPERES is unknown while VOLTS and OHMS are
known, use the following formula:

OHMS

If VOLTS is unknown while AMPERES and OHMS are
known, use the following formula:

If OHMS is unknown but VOLTS and AMPERES are
known, use the following:

AMPERES

AMPERES =

VOLTS = AMPERES x OHMS

OHMS

VOLTS

VOLTS

=

Page 15

STATOR

ROTOR

ENGINE

CAPACITOR

DIODE B

COIL 2

COIL 1

DIODE A

CAPACITOR

STATOR

EXCITATION

WINDING

STATOR

POWER

WINDING

STATOR
POWER

WINDING

MAGNETIC

FIELD

MAGNETIC

FIELD

MLB = MAIN LINE
CIRCUIT BREAKER

ROTOR

TO LOAD

MLB

ENGINE ­DIRECT
DRIVE

AUTOMATIC

VOLTAGE

REGULATOR

+-

STATOR

EXCITATION

WINDING

STATOR
POWER

WINDING

STATOR
POWER

WINDING

MAGNETIC

FIELD

MAGNETIC

FIELD

SENSING

MLB = MAIN LINE
CIRCUIT BREAKER

ROTOR

TO LOAD

MLB

ENGINE -
DIRECT
DRIVE

120 VAC 120 VAC

240 VAC

120 VAC 120 VAC

240 VAC

SECTION 1.3

BRUSHLESS, CAPACITOR EXCITATION SYSTEM

PART 1

GENERAL INFORMATION

INTRODUCTION

A typical brushless type portable generator will need
4 major components to function—a prime mover, a
stator, a rotor, and a capacitor.

As the engine starts to crank, residual magnetism
from the rotor creates magnetic lines of flux. The
lines begin to cut the excitation winding and induce
a small voltage into the winding. The voltage causes
the capacitor to charge. When the capacitor has fully
charged it will discharge a voltage that will be induced
back into the rotor. The AC voltage induced into the
rotor is rectified using a diode. The magnetic lines of
flux from the rotor will increase, causing output volt­age to increase. The charge and discharge relation­ship that the capacitor and rotor share is the voltage
regulation system that allows the generator to main­tain 240 volts.

Figure 1 shows the major components of a typical GP
Series brushless AC generator.

a tapered crankshaft and is held in place with a single
through bolt.

Note: Some Rotors have a magnet placed inside
to help excite the rotor after it has been left idle
for a long period of time.

Figure 2. Rotor and Diodes

Figure 1. AC Generator Exploded View

The stator has three windings wound separately
inside the can. Two are the power windings and are

STATOR ASSEMBLY

located on Wire 44 (Hot) and Wire 33 (Neutral), the
other winding is located on Wire 11 (Hot) and Wire 22
(Neutral). The third winding is called the DPE winding
or Displaced Phase Excitation winding and is located
on Wire 2 and Wire 6.

The 2-pole rotor must be operated at 3600 rpm to
supply a 60 Hertz AC frequency. The term “2-pole”
means the rotor has a single north magnetic pole and
a single south magnetic pole. It spins freely inside
the stator can and is excited by the charging and dis­charging of the capacitor. It has two diodes that rec­tify voltage induced from the Excitation winding to DC
voltage. The rotor bearing is pressed onto the end of
the rotor shaft. The tapered rotor shaft is mounted to

Page 16

ROTOR ASSEMBLY

CIRCUIT BREAKERS

Each individual circuit on the generator is protected
by a circuit breaker to prevent overload.

Figure 3. Generator Operating Diagram

GENERAL INFORMATION

CAPACITOR 28µf

WIRE 2

WIRE 6

RED (R2 – 33)

BLUE (R1 – 44)

BROWN (L2 – 22)

WHITE (L1 – 11)

WIRE 2

WIRE 6

11 22 33 44

CAPACITOR 47µf (440 VAC)

PART 1

SECTION 1.3

BRUSHLESS, CAPACITOR EXCITATION SYSTEM

OPERATION

STARTUP:
When the engine is started, residual magnetism from

the rotor induces a voltage into (a) the stator AC
power windings, (b) the stator excitation or DPE wind­ings. In an “On-speed” (engine cranking) condition,
residual magnetism is capable of creating approxi­mately one to three Volts AC.

ON-SPEED OPERATION:
As the engine accelerates, the voltage that is induced

into the stator windings increases rapidly, due to the
increasing speed at which the rotor operates.

FIELD EXCITATION:
An AC voltage is induced into the stator excitation

(DPE) windings. The DPE winding circuit is completed
to the capacitor where the charging and discharging
causes a voltage to be induced back in to the rotor
which will regulate voltage. The greater the current
flow through the rotor windings, the more concen­trated the lines of flux around the rotor become. The
more concentrated the lines of flux around the rotor
that cut across the stationary stator windings, the
greater the voltage that is induced into the stator
windings. Initially, the AC power winding voltage is
low, but as the capacitor is charged and discharged
this relationship between the rotor and the capacitor
is what will regulate voltage at a desired level.

AC POWER WINDING OUTPUT:
A regulated voltage is induced into the stator AC

power windings. When electrical loads are connected
across the AC power windings to complete the circuit,
current can flow in the circuit.

A

Figure 4. Alternator Configuration A

B

Figure 5. Alternator Configuration B

Page 17

STATOR

ROTOR

ENGINE

BRUSHES

VOLTAGE REGULATOR

Section 1.4
BRUSHED EXCITATION SYSTEM

PART 1

GENERAL INFORMATION

INTRODUCTION

A typical brushed type portable generator will need 4
major components to function: a prime mover, a sta­tor, a rotor, and a voltage regulator.

As the engine starts to crank, residual magnetism
from the rotor creates magnetic lines of flux. The lines
begin to cut the excitation winding and induce a small
voltage into the voltage regulator. The excitation volt­age will power the voltage regulator and the voltage
regulator will start to sense AC voltage from Wires
S15 and S16. The lower voltage from the sensing
wires will cause DC excitation to the rotor to be driven
up until AC output is at desired level of 240VAC. Once
the generator has reached 240VAC it will maintain the
DC voltage, regulating the alternator when loads are
applied and removed.

to the negative (-) slip ring and brush on Wire 0. This
current flow creates a magnetic field around the rotor
having a flux concentration that is proportional to the
amount of current flow.

ROTOR RESIDUAL MAGNETISM

The generator revolving field (rotor) may be consid­ered to be a permanent magnet. Some “residual”
magnetism is always present in the rotor. This residu­al magnetism is sufficient to induce a voltage into the
stator AC power windings that is approximately 2-5
volts AC.

Note: Some Rotors have a magnet placed inside
to help excite the rotor after it has been left idle
for a long period of time.

VOLTAGE REGULATOR

Refer to Figure 3 for the proper identification of the
voltage regulator. Unregulated AC output from the
stator excitation winding is delivered to the regulator’s
DPE terminals, via Wire 2 and Wire 6. The voltage
regulator rectifies that current and, based on stator
AC power winding sensing, regulates it. The rectified
and regulated excitation current is then delivered to
the rotor windings from the positive (+) and negative
(-) regulator terminals, via Wire 4 and Wire 0. Stator
AC power winding “sensing” is delivered to the regula­tor via Wires S15 and S16.

Figure 1. AC Generator Exploded View

STATOR ASSEMBLY

The stator has three windings wound separately
inside the can. Two are the power windings and are
located on Wire 44 (Hot) and Wire 33 (Neutral); the
other winding is located on Wire 11 (Hot) and Wire 22
(neutral). The third winding is called DPE winding or
Displaced Phase Excitation winding and is located on
Wire 2 and Wire 6.

BRUSH HOLDER AND BRUSHES

The brush holder is retained to the rear bearing car­rier by means of two Taptite screws. A positive (+) and
a negative (-) brush are retained in the brush holder.
Wire 4 connects to the positive (+) brush and Wire
0 to the negative (-) brush. Rectified and regulated
excitation current are delivered to the rotor windings
via Wire 4, and the positive (+) brush and slip ring.
The excitation current passes through the windings

Page 18

OPERATION

STARTUP:
When the engine is started, residual magnetism from

the rotor induces a voltage into (a) the stator AC
power windings, (b) the stator excitation or DPE wind­ings. In an “on-speed” (engine cranking) condition,
residual magnetism is capable of creating approxi­mately one to three volts AC.

ON-SPEED OPERATION:
As the engine accelerates, the voltage that is induced

into the stator windings increases rapidly, due to the
increasing speed at which the rotor operates.

FIELD EXCITATION:
An AC voltage is induced into the stator excitation

(DPE) windings. The DPE winding circuit is com­pleted to the voltage regulator, via Wire 2 and Wire

6. Unregulated alternating current can flow from the
winding to the regulator. The voltage regulator “sens­es” AC power winding output voltage and frequency
via stator Wires S15 and S16.

The regulator changes the AC from the excitation
winding to DC. In addition, based on the Wire S15
and Wire S16 sensing signals, it regulates the flow of
direct current to the rotor. The rectified and regulated
current flow from the regulator is delivered to the rotor
windings, via Wire 4, and the positive brush and slip
ring. This excitation current flows through the rotor

GENERAL INFORMATION

AUTOMATIC

VOLTAGE

REGULATOR

+-

STATOR

EXCITATION

WINDING

STATOR
POWER

WINDING

STATOR
POWER

WINDING

MAGNETIC

FIELD

MAGNETIC

FIELD

SENSING

MLB = MAIN LINE
CIRCUIT BREAKER

ROTOR

TO LOAD

MLB

ENGINE ­DIRECT
DRIVE

120 VAC 120 VAC

240 VAC

VOLTAGE REGULATOR

AVR SENSING

DPE

NOT USED

RED (R2 – 11)

BLUE (R1 – 22)

BLUE

BLUE

4 (+) RED

S15

2

S16

6

0 (-) WHITE

BROWN (L2 – 33)

WHITE (L1 – 44)

WHITE

GREEN

C1 FEMALE

C1 MALE

PART 1

windings and through the negative (-) slip ring and
brush on Wire 0.

The greater the current flow through the rotor wind­ings, the more concentrated the lines of flux around
the rotor become. The more concentrated the lines
of flux around the rotor that cut across the stationary
stator windings, the greater the voltage that is induced
into the stator windings.

Initially, the AC power winding voltage sensed by the
regulator is low. The regulator reacts by increasing
the flow of excitation current to the rotor until volt­age increases to a desired level. The regulator then
maintains the desired voltage. For example, if voltage
exceeds the desired level, the regulator will decrease
the flow of excitation current. Conversely, if voltage
drops below the desired level, the regulator responds
by increasing the flow of excitation current.

AC POWER WINDING OUTPUT:
A regulated voltage is induced into the stator AC

power windings. When electrical loads are connected
across the AC power windings to complete the circuit,
current can flow in the circuit.

Section 1.4

BRUSHED EXCITATION SYSTEM

Figure 2. 240 VAC Sensing Alternator

C

Figure 3. Alternator Configuration C

Page 19

NOTES

Page 20

PART 2

AC GENERATORS

GP Series Portable Generators

TABLE OF CONTENTS

PART TITLE PAGE#

2.1 Brushless Excitation
Troubleshooting Flowcharts

2.2 Brushed Capacitor
Troubleshooting Flowcharts

2.3 AC Diagnostic Tests 26

22

24

Part 2 – AC Generators ......................................... 21

Section 2.1 – Brushless Capacitor

Troubleshooting Flowcharts ............. 22

Section 2.2 – Brushed Excitation

Troubleshooting Flowcharts ............. 24

Section 2.3 – AC Diagnostic Tests ........................ 26

Introduction ......................................................26

Test 1 – Check No-Load Voltage

and Frequency ....................................26

Test 2 – Check Circuit Breaker.........................26

Test 3 – Check Continuity of

Receptacle Panel ................................26

Test 4 – Field Flash Alternator

(Configuration “A” Only) .......................27

Test 5 – Check Brushed Rotor Circuit ..............28

Test 6 – Check Capacitor .................................29

Test 7 – Test Brushless DPE Winding ..............30

Test 8 – Test Brushless Stator Windings ..........30

Test 9 – Test Brushed Stator Windings ............31

Test 10 – Check Load Voltage & Frequency ....31

Test 11 – Check Load Watts & Amperage .......31

Test 12 – Adjust Voltage Regulator ..................31

Page 21

SECTION 2.1

GO TO PROBLEM 2 GO TO PROBLEM 1GO TO PROBLEM 4 VERIFY ROTOR IS SPINNING,

GO TO PROBLEM 1

GO TO PROBLEM 3

VOLTAGE &

FREQUENCY BOTH

HIGH OR LOW

FREQUENCY GOOD

VOLTAGE HIGH

ZERO VOLTAGE

ZERO FREQUENCY

FREQUENCY GOOD,

LOW OR RESIDUAL

VOLTAGE

TEST 1 - CHECK

NO LOAD VOLTAGE

& FREQUENCY

NO LOAD VOLTAGE &

FREQUENCY GOOD -

VOLTAGE/FREQUENCY

FALLS OFF UNDER LOAD

If Problem Involves AC Output

REPLACE

ALTERNATOR

REPLACE

ROTOR

STOP TESTING

BAD

BAD

GOOD

GOOD

CONFIGURATION “B”

GOOD

CONFIGURATION “A”

BAD

CONFIGURATION “B”

BAD

CONFIGURATION “A”

Problem 1 – Generator Produces Zero Voltage or Residual Voltage

TEST 2 – CHECK

MAIN CIRCUIT

BREAKER

RESET TO “ON”

OR REPLACE IF BAD

REPLACE COMPONENT

AS NEEDED

STOP

TESTING

TEST 3 – CHECK

CONTINUITY OF

RECEPTACLE PANEL

RE-CHECK VOLTAGE

AT RECEPTACLE

PANEL

RE-CHECK VOLTAGE

AT RECEPTACLE

PANEL

TEST 4 – FIELD

FLASH

ALTERNATOR

REPLACE

BAD

BAD

BAD

REPLACE

S TATO R

BAD

REPLACE

ALTERNATOR

REPLACE

CAPACITOR

ON

GOOD

GOODGOODGOOD

TEST 6 –

CHECK

CAPACITOR

TEST 7 – TEST

BRUSHLESS

DPE WINDING

TEST 8 – TEST

BRUSHLESS

STATOR

WINDINGS

TEST STATOR
FOR SHORTS

TO GROUND

GOOD

BRUSHLESS CAPACITOR TROUBLESHOOTING FLOWCHARTS

PART 2

AC GENERATORS

The GP series portable generators currently use
three different types of alternators. Two of the alterna­tors are brushless capacitor type with different style of
capacitors (Configuration “A” and “B”). The third uti­lizes a voltage regulator and a brushed excitation sys­tem (Configuration “C”). To help with troubleshooting,
two sets of flow charts have been created for these
different styles of alternators.

Identify the configuration of the alternator being ser­viced using Sections 1.3 and 1.4 of this manual and
proceed to the appropriate flowchart section.

Configuration “A” – Brushless Capacitor, use Section 2.1

Configuration “B” – Brushless Capacitor, use Section 2.1

Configuration “C” – Brushed Excitation, use Section 2.2

Page 22

AC GENERATORS

TEST 40 – CHECK & ADJUST ENGINE

GOVERNOR, 389cc ENGINE

TEST 41 – CHECK & ADJUST ENGINE

GOVERNOR, 410cc ENGINE

GO TO

PROBLEM 1

GO TO

PROBLEM 3

GO TO PROBLEM 1,

TEST 6 – CHECK

CAPACITOR

Problem 2 – V

oltage & Frequency Are Both High or Low

FREQUENCY GOOD, LOW OR

RESIDUAL VOLTAGE

FREQUENCY IS GOOD BUT
NO-LOAD VOLTAGE IS HIGH

NO-LOAD FREQUENCY & VOLTAGE GOOD BUT

THEY DROOP TO MUCH WHEN LOAD IS APPLIED

CONFIGURATION “B”

CONFIGURATION “A”

REPLACE

ALTERNATOR

STOP

TESTING

RE-CHECK VOLTAGE

AT RECEPTACLE

PANEL

REPLACE

CAPACITOR

GOOD

BAD

GO TO PROBLEM 12

GO TO PROBLEM 23

REDUCE LOAD

END TEST

Problem 3 – Excessive Voltage/Frequency Droop When Load is Applied

TEST 10 – CHECK

LOAD VOLTAGE &

FREQUENCY

TEST 11 – CHECK

LOAD WATTS &

AMPERAGE

GOOD

GOOD GOOD

BAD

OVERLOADED

NOT OVERLOADED

TEST 41 – CHECK

& ADJUST

ENGINE

GOVERNOR,

410cc ENGINE

TEST 40 – CHECK

& ADJUST

ENGINE

GOVERNOR,

389cc ENGINE

CONFIGURATION “B”

STOP

TESTS

REPLACE

Problem 4 – Generator Produces High Voltage at No-Load

TEST 1 – CHECK

NO-LOAD VOLTAGE

AND FREQUENCY

FREQUENCY AND

VOLTAGE O.K.

FREQUENCY O.K.,

BUT VOLTAGE HIGH

FREQUENCY

HIGH

BAD

GO TO “PROBLEM 1”,
TEST 7 – TEST BRUSHLESS
DPE WINDING

FREQUENCY O.K., BUT

VOLTAGE IS STILL HIGH

TEST 6 –

CHECK

CAPACITOR

TEST 40 – CHECK & ADJUST ENGINE

GOVERNOR, 389cc ENGINE

TEST 41 – CHECK & ADJUST ENGINE

GOVERNOR, 410cc ENGINE

GOOD

CONFIGURATION “A”

REPLACE

ALTERNATOR

STOP

TESTING

RE-CHECK VOLTAGE AT

RECEPTACLE PANEL

REPLACE

CAPACITOR

GOOD

BAD

PART 2

SECTION 2.1

BRUSHLESS CAPACITOR TROUBLESHOOTING FLOWCHARTS

Page 23

SECTION 2.2

GO TO PROBLEM 6 GO TO PROBLEM 5GO TO PROBLEM 5 GO TO PROBLEM 7

VOLTAGE &

FREQUENCY BOTH

HIGH OR LOW

FREQUENCY GOOD

VOLTAGE HIGH

ZERO VOLTAGE

ZERO FREQUENCY

FREQUENCY GOOD,

LOW OR RESIDUAL

VOLTAGE

TEST 1 - CHECK

NO LOAD VOLTAGE

& FREQUENCY

NO LOAD VOLTAGE &

FREQUENCY GOOD -

VOLTAGE/FREQUENCY

FALLS OFF UNDER LOAD

If Problem Involves AC Output

VERIFY ROTOR IS SPINNING,

GO TO PROBLEM 5

REPLACE

BRUSHES

STOP TESTING

BAD

BAD

BAD

GOOD

Problem 5 – Generator Produces Zero Voltage or Residual Voltage

TEST 2 – CHECK

MAIN CIRCUIT

BREAKER

RESET TO “ON”

OR REPLACE IF BAD

REPLACE COMPONENT

AS NEEDED

TEST 3 – CHECK

CONTINUITY OF

RECEPTACLE PANEL

TEST 5 – CHECK

BRUSHES

REPLACE

ALTERNATOR

REPLACE AUTOMATIC

VOLTAGE REGULATOR

TEST 12 – ADJUST

AUTOMATIC VOLTAGE

REGULATOR

ON

GOOD

GOOD

STOP TESTING

GOOD

BAD

RE-CHECK VOLTAGE

AT RECEPTACLE

PANEL

BRUSHED EXCITATION TROUBLESHOOTING FLOWCHARTS

PART 2

AC GENERATORS

The GP series portable generators currently use
three different types of alternators. Two of the alterna­tors are brushless capacitor type with different style of
capacitors (Configuration “A” and “B”). The third uti­lizes a voltage regulator and a brushed excitation sys­tem (Configuration “C”). To help with troubleshooting,
two sets of flow charts have been created for these
different styles of alternators.

Identify the configuration of the alternator being ser­viced using Sections 1.3 and 1.4 of this manual and
proceed to the appropriate flowchart section.

Configuration “A” – Brushless Capacitor, use Section 2.1

Configuration “B” – Brushless Capacitor, use Section 2.1

Configuration “C” – Brushed Excitation, use Section 2.2

Page 24

AC GENERATORS

TEST 40 – CHECK & ADJUST ENGINE

GOVERNOR, 389cc ENGINE

TEST 41 – CHECK & ADJUST ENGINE

GOVERNOR, 410cc ENGINE

GO TO

PROBLEM 5

GO TO

PROBLEM 7

GO TO PROBLEM 5,

TEST 12 – ADJUST

VOLTAGE

REGULATOR

Problem 6 – V

oltage & Frequency Are Both High or Low

FREQUENCY GOOD,

LOW OR RESIDUAL

VOLTAGE

FREQUENCY IS GOOD

BUT NO-LOAD

VOLTAGE IS HIGH

NO-LOAD FREQUENCY &

VOLTAGE GOOD BUT THEY

DROOP TO MUCH WHEN

LOAD IS APPLIED

GO TO PROBLEM 12

GO TO PROBLEM 23

REDUCE LOAD

END TEST

Problem 7 – Excessive Voltage/Frequency Droop When Load is Applied

TEST 10 – CHECK

LOAD VOLTAGE &

FREQUENCY

TEST 11 – CHECK

LOAD WATTS &

AMPERAGE

GOOD

GOOD GOOD

BAD

OVERLOADED

NOT OVERLOADED

TEST 41 – CHECK

& ADJUST

ENGINE

GOVERNOR,

410cc ENGINE

TEST 40 – CHECK

& ADJUST

ENGINE

GOVERNOR,

389cc ENGINE

BAD

STOP

TESTS

Problem 8 – Generator Produces High Voltage at No-Load

FREQUENCY AND

VOLTAGE O.K.

FREQUENCY O.K.,

BUT VOLTAGE IS

STILL HIGH

TEST 40 – CHECK & ADJUST ENGINE

GOVERNOR, 389cc ENGINE

TEST 41 – CHECK & ADJUST ENGINE

GOVERNOR, 410cc ENGINE

TEST 1 – CHECK

NO-LOAD VOLTAGE

AND FREQUENCY

FREQUENCY O.K.,

BUT VOLTAGE HIGH

FREQUENCY

HIGH

REPLACE AUTOMATIC

VOLTAGE REGULATOR

TEST 12 – ADJUST

AUTOMATIC VOLTAGE

REGULATOR

GOOD

RE-CHECK VOLTAGE

AT RECEPTACLE

PANEL

REPLACE

ALTERNATOR

PART 2

SECTION 2.4

BRUSHED EXCITATION TROUBLESHOOTING FLOWCHARTS

Page 25

240

00.01

C.B.

20/30A

SECTION 2.3

AC DIAGNOSTIC TESTS

PART 2

AC GENERATORS

INTRODUCTION

The “Diagnostic Tests” in this chapter may be per­for med in conjunction with the “Flow Charts” of
Section 2.1 and Section 2.2. Test numbers in this
chapter correspond to the numbered tests in the
“Flow Charts”. It may be helpful to read Section 1.2,
“Measuring Electricity.”

NOTE: Test procedures in this Manual are not nec­essarily the only acceptable methods for diagnos­ing the condition of components and circuits. All
possible methods that might be used for system
diagnosis have not been evaluated. If any diag­nostic method is used other than the method pre­sented in this Manual, the technician must ensure
that neither his personal safety nor the product's
safety will be endangered by the procedure or
method that has been selected.

For visual pictures of the different configurations
of the stators and the wire numbers associated
with different components please see Figures 4
and 5 in Section 1.3, and Figure 3 in Section 1.4.

TEST 1 – CHECK NO-LOAD VOLTAGE AND

FREQUENCY

PROCEDURE:

1. Disconnect or turn OFF all electrical loads connected to
the generator.

TEST 2 – CHECK CIRCUIT BREAKER

PROCEDURE:
The generator has circuit breakers located on the

control panel. If outlets are not receiving power, make
sure the breakers are set to ON or “Closed”.

If a breaker is suspected to have failed, it can be
tested as follows:

1. Set a VOM to measure resistance.

2. With the generator shut down, disconnect all wires from the
suspected circuit breaker terminals to prevent interaction.

3. With the generator shut down, connect one meter test
lead to a one terminal of the breaker and the other
meter test lead to the other terminal. See Figure 2.

4. Set the breaker to its ON or “Closed” position. The meter
should read CONTINUITY.

5. Set the breaker to its OFF or “Open” position and the
meter should indicate INFINITY.

2. Set a VOM to measure AC voltage.

3. Reset all circuit breakers to the on position.

4. Start the engine and let it stabilize and warm up.

Figure 1. VOM Test Leads Connected to a 240 VAC

receptacle

6. Place the meter test leads into an outlet. See Figure 1.

7. Read the AC voltage.

8. Connect a AC frequency meter as described in Step 6.

9. Read the AC frequency.

RESULTS:

No Load Voltage

223.2 – 256.8 VAC 62.5 – 62.0 HZ

Refer back to Flow Chart.

Page 26

No Load Frequency

Figure 2. 20/30 Amp Breaker Test Points

RESULTS:

1. If the circuit breaker tests good, refer back to the flow
chart.

2. If the breaker tests bad, it should be replaced.

TEST 3 – CHECK CONTINUITY OF

RECEPTACLE PANEL

DISCUSSION:
Continuity of the receptacle panel is important

because it reflects that the receptacle has continuity
through the wiring and is physically connected to the
stator. Most stator winding values are between 0.01
and 0.02 Ohms of resistance. If a higher than normal
ohm reading is shown then a poor connection could
be the problem preventing that receptacle from receiv­ing power.

PROCEDURE:

1. Set a VOM to measure Resistance.

AC GENERATORS

0.01 Ohms

12 AWG12 AWG

MOMENTARY PUSHBUTTON ON/OFF SWITCH

SINGLE POLE SWITCH ON LIVE SIDE

 DO NOT SUBSTITUTE ANY OTHER DEVICE

4 ft.

CRIMP ON STANDARD
FEMALE BLADE
CONNECTORS

STANDARD

MALE PLUG

PART 2

SECTION 2.3

AC DIAGNOSTIC TESTS

2. Connect a VOM as shown in Figure 3 to each receptacle
on the unit.

Note: Only one outlet on each receptacle needs to
be tested.

RESULTS:

1. If any other reading than continuity was measured fur­ther troubleshooting will need to be done to determine if
it is the receptacle or the wiring.

2. If receptacles test good, refer back to flow chart.

TEST 4 – FIELD FLASH ALTERNATOR

(CONFIGURATION “A” ONLY)

DISCUSSION:
The alternator utilizes residual magnetism within the

windings to charge the capacitor. If the generator has
been sitting for a long period of time with no activity
the residual magnetism could be lost within the rotor.
Field flashing the rotor while connected in parallel with
the capacitor will force a charge of electricity through
the DPE winding. The voltage that is induced into the
rotor will in turn charge the rotor with enough residual
magnetism that it will be able to charge the capacitor
during normal operation.

Warning:

performing this test.

*

PROCEDURE:

1. Construct an energizing cord that is similar to that shown
in Figure 4 and connect it as shown in Figure 5 on the
next page.

2. Set the START-RUN-STOP switch to the OFF position.

Warning:

more than 1 second at a time.

*

3. Momentarily turn on the energizing cord (one second).

Please keep safety in mind while

Do NOT energize the capacitor for

Figure 3. Checking Continuity of Receptacles

Figure 4. Construction of Energizing Cord

4. Disconnect the energizing cord from the capacitor.

5.

If the field flash was successful, the generator should now

be producing approximately 240 VAC at the main circuit
breaker of the generator when the START-RUN-STOP is
set to the START position.

Page 27

+

–

SECTION 2.3

CAPACITOR

DEPRESS SWITCH FOR

ONE SECOND

PLUG ENERGIZING CORD

INTO AC OUTLET

CAPICITOR REMAINS CONNECTED

TO GENERATOR





Danger: The capacitor may need to be
discharged before testing. A capacitor can
be discharged by crossing the terminals
with a metal insulated screw driver.

Danger: Use proper protective equipment
when dealing with a capacitor that has
exploded.

AC DIAGNOSTIC TESTS

PART 2

AC GENERATORS

Figure 5. Connecting Energizing Cord

Warning:

than two times in sequence. If the unit has

*

not produced power after two attempts, other
issues exist and need to be addressed.

RESULTS:

Do not field flash alternator more

3. Inspect the rotor slip rings. If they appear dull or tar­nished, they may be polished with fine sandpaper. DO
NOT USE METALLIC GRIT TO POLISH SLIP RINGS.

1. Refer back to flow chart.

TEST 5 – CHECK BRUSHES

DISCUSSION:
The function of the brushes and slip rings is to pro-

vide passage of excitation current from stationary
components to the rotating rotor. Brushes are made
of a special long lasting material and seldom wear
out or fail. However, slip rings can develop a tarnish or
film that can inhibit or offer a resistance to the flow of
electricity. Such a non-conducting film usually devel­ops during non-operating periods. Broken or discon­nected wiring can also cause loss of excitation current
to the rotor.

PROCEDURE:

1. See Figure 6. Carefully inspect brush wires. Make sure

2. Disconnect the red and white wire from the brush assem-

they are properly and securely connected.

bly. Remove the brush assembly from the bearing car­rier. Inspect the brushes for excessive wear, or damage.

Figure 6. Brushes and Slip Rings

RESULTS:

1. Repair, replace or reconnect wires as necessary.

2. Replace any damaged slip rings or brush holder.

3. Clean and polish slip rings as required.

4. If brush assembly and slip rings look good proceed to
Step 5.

Page 28

AC GENERATORS

SET TO READ
CAPACITANCE

59.0 µf

SET TO READ
CAPACITANCE

28.0 µf

CAPACITOR 28µf

PART 2

TEST 6 – CHECK CAPACITOR

DISCUSSION:
The brushless rotor system relies on the charging and

discharging of a capacitor to induce voltage into the
rotor and also to regulate voltage once 240 VAC is
achieved. If the capacitor fails, only residual magne­tism of the rotor will be measured at the Main Breaker.

Warning: The capacitor may need to be dis-

charged before testing. A capacitor can be

*

discharged by crossing the terminals with a
metal insulated screw driver.

Warning: Use proper protective equipment

when dealing with a capacitor that has

*

exploded.

PROCEDURE:

1. Consult the owner’s manual of the meter being used for
directions on measuring capacitance. Figures 7 and 8
show a typical meter and how to check capacitance.

SECTION 2.3

AC DIAGNOSTIC TESTS

2. Connect the meter leads directly across the terminals of
the capacitor. The rated µf (micro farad) of the capacitor
is marked on the side of the canister.

3. The meter should display the correct µf reading ± 5µf.
If anything other than the indicated rating is displayed,
replace the capacitor.

RESULTS:

1. Refer back to flow chart

2. Common observations can be made by visually inspect­ing the capacitor.

a. A capacitor that has gone bad can have a ten-

dency to explode. Use caution when dealing
with an exploded capacitor, the gel from inside
a capacitor can cause skin irritation.

b. A capacitor is defective if the terminal connec-

c. A capacitor is defective if it wobbles while sitting

d. If any of the above observations are observed,

tions are loose on the canister.

on a flat surface.

replace the capacitor.

Figure 7. Capacitor Test Points

(Alternator Configuration “A”)

Figure 8. Capacitor Test Points

(Alternator Configuration “B”)

Page 29

SECTION 2.3

AC DIAGNOSTIC TESTS

PART 2

AC GENERATORS

TEST 7 – TEST BRUSHLESS DPE WINDING

DISCUSSION:
A DPE or Displaced Phase Excitation winding is used

to charge a capacitor, which discharges and charges,
releasing a voltage that is induced into the rotor. If
the DPE winding fails, only residual magnetism of the
rotor will be measured at the Main Breaker.

Note: The resistance of stator windings is very
low. Some meters will not read such a low resis­tance, and will simply indicate CONTINUITY.
Recommended is a high quality, digital type meter
capable of reading very low resistances.

Danger: The capacitor may need to be dis­charged before testing. A capacitor can be

*

discharged by crossing the terminals with
a metal insulated screw driver.

PROCEDURE:

1. Disconnect Wire 2 and Wire 6 from the capacitor.

2. Set VOM to measure resistance.

3. Connect one meter lead to Wire 2 and connect the other
meter lead to Wire 6.

a. Reading should be approximately 0.97 and 1.13

Ohms.

4. Connect one meter lead to Wire 2 and connect the other
meter lead to a clean frame ground, INFINITY should be
measured.

5. Isolate the stator wire so that the stator is disconnected
from the receptacle panel and the capacitor.

Note: Isolate all main stator leads before proceeding.

6. Connect one meter lead to Wire 2 and connect the other
meter lead to Wire 11. INFINITY should be measured.

TEST 8 – TEST BRUSHLESS STATOR WINDINGS

DISCUSSION:
The brushless stator has three internal windings,

two main power windings and a DPE winding. This
test will ensure that there are no shorts between the
power windings or shorts to ground.

A VOM meter can be used to test the stator windings
for the following faults:

• Anopencircuitcondition

• A“short-to-ground”condition

• Ashortcircuitbetweenwindings

Note: The resistance of stator windings is very
low. Some meters will not read such a low resis­tance, and will simply indicate CONTINUITY.
Recommended is a high quality, digital type meter
capable of reading very low resistances.

Note: Refer to Figure 4 in Section 1.3 for illustra­tion of Stator Configuration “A”. Some wire num­bers will not be marked on the stator.

PROCEDURE:

1. Disconnect Wires 11, 22, 33, 44 from the receptacle
panel so that the stator is isolated.

2. Make sure all of the disconnected leads are isolated
from each other and are not touching the frame during
the test.

3. Set a VOM to measure resistance.

4. Connect one test lead to Stator Lead 11. Connect the
other test lead to Stator Lead 22. Stator resistance
should be between 0.12-0.14 Ohms.

5. Connect one test lead to Stator Lead 33. Connect the
other test lead to Stator Lead 44. Stator resistance
should be between 0.12-0.14 Ohms.

7. Repeat Step 6 using Wire 2 and Wire 44.INFINITY
should be measured.

RESULTS:

1. Stator winding resistance values is a test of winding conti­nuity and resistance. If a very high resistance or INFINITY
is indicated, the winding is open or partially open.

2. Testing for a “grounded” condition: Any resistance read­ing indicates that the winding is grounded.

3. Testing for a “shorted” condition: Any resistance reading
indicates that the winding is shorted.

4. If stator tests good and wire continuity tests good, refer
back to flow chart.

Page 30

TEST WINDINGS FOR A SHORT TO GROUND:

1. Make sure all leads are isolated from each other and are
not touching the frame.

2. Connect one test lead to a clean frame ground. Connect
the other test lead to Stator Lead Wire 11.

a. The meter should read INFINITY.
b. Any reading other than INFINITY indicates a

“short to ground” condition.

3. Repeat Step 2 using Stator Lead 44

TEST FOR A SHORT CIRCUIT BETWEEN WINDINGS:

1. Connect one test lead to Stator Lead 11. Connect the
other test lead to Stator Lead 33.

a. The meter should read INFINITY.
b. Any reading other that INFINITY indicates a

short between windings.

AC GENERATORS

240

PART 2

SECTION 2.3

AC DIAGNOSTIC TESTS

TEST 9 – TEST BRUSHED STATOR WINDINGS

DISCUSSION:
Most brushed stators have three main windings that

are needed to produce voltage. The alternator has
two main power windings that supply power to the
load and a DPE winding to provide excitation voltage
to the rotor. It is important that these windings remain
isolated from ground or the chassis of the alternator.

PROCEDURE:

1. Isolate all stator wires from the control panel and the
voltage regulator.

2. Set a VOM to measure resistance.

3. Refer to Configuration “C” in Section 1.4 for proper test
points for checking the stator. Every connection needs to
be checked coming out of the stator for a short to ground.

RESULTS:

1. If any wire has a direct short to ground or to the chassis
of the alternator replace the alternator assembly.

2. If all wires test good for a short to ground, refer back to
flow chart.

RESULTS:

1. If the unit is overloaded, reduce the load.

2. If load is within limits, but frequency and voltage still drop
excessively, refer back to Flow Chart.

Overloading a generator in excess of its rated wattage
capacity can result in damage to the generator and to
connected electrical devices. Observe the following to
prevent overloading the unit:

• Addupthe total wattageofall electrical devicesto

be connected at one time. This total should NOT be
greater than the generator's wattage capacity.

• Theratedwattage oflightscanbe takenfromlight

bulbs. The rated wattage of tools, appliances and
motors can usually be found on a data label or
decal affixed to the device.

• If the appliance,tool or motor does not give watt-

age, multiply volts times ampere rating to determine
watts (volts x amps = watts).

• Some electric motors, such as induction types,

require about three times more watts of power for
starting than for running. This surge of power lasts
only a few seconds when starting such motors.

Make sure to allow for high starting wattage when
selecting electrical devices to connect to the generator:

1. Figure the watts needed to start the largest motor.

TEST 10 – CHECK LOAD VOLTAGE &

FREQUENCY

PROCEDURE:
Perform this test in the same manner as Test 1, but

apply a load to the generator equal to its rated capacity.
With load applied check voltage and frequency.

Frequency should not drop below about 59 Hertz with
the load applied.

Voltage should not drop below about 220 VAC nor rise
above 265 VAC with load applied.

RESULTS:

1. If voltage and/or frequency drop excessively when the
load is applied, refer back to flow chart.

2. If load voltage and frequency are within limits, end tests.

TEST 11 – CHECK LOAD WATTS & AMPERAGE

PROCEDURE:
Add up the wattages or amperages of all loads pow-

ered by the generator at one time. If desired, a clamp­on ammeter may be used to measure current flow.
See “Measuring Current” in Section 1.2.

A Wattage Reference Guide is provided on the next
page to assist in determining how many items the
generator can operate at one time.

NOTE: All figures are approximate. See data label
on appliance for wattage requirements.

2. Add to that figure the running watts of all other con­nected loads.

TEST 12 – ADJUST VOLTAGE REGULATOR

PROCEDURE:

1. Remove cover from end of alternator assembly.

2. Remove two screws holding down the voltage regulator
(AVR); refer to Figure C in Section 1.4 for identification.

3. Leave AVR connected to stator and brushes

4. Set VOM to measure AC voltage.

5. Connect VOM across a 240VAC socket as shown in
Figure 9.

Figure 9. VOM Test Leads Connected to a 240 VAC

receptacle

Page 31

SECTION 2.3

AC DIAGNOSTIC TESTS

6. Ensure all material is clear of the alternator before pro­ceeding.

7. Set START-STOP-RUN switch to START

8. Refer to Figure 10 for location of adjustment screw.

9. Adjusting screw clockwise will increase voltage, adjust­ing counterclockwise will lower the voltage.

RESULTS:

1. If no change in voltage while adjusting refer back to flow
chart.

2. If voltage is correct, stop testing.

PART 2

Figure 10. Voltage Regulator Adjustment Screw

AC GENERATORS

WATTAGE REFERENCE GUIDE

Device Running

Watts

*Air Conditioner (12,000 Btu) 1700
*Air Conditioner (24,000 Btu) 3800
*Air Conditioner (40,000 Btu) 6000
Battery Charger (20 Amp) 500
Belt Sander (3") 1000
Chain Saw 1200
Circular Saw (6-1/2") 800 to 1000
*Clothes Dryer (Electric) 5750
*Clothes Dryer (Gas) 700
*Clothes Washer 1150
Coffee Maker 1750
*Compressor (1 HP) 2000
*Compressor (3/4 HP) 1800
*Compressor (1/2 HP) 1400
Curling Iron 700
*Dehumidifier 650
Disc Sander (9") 1200
Edge Trimmer 500
Electric Blanket 400
Electric Nail Gun 1200
Electric Range (per element) 1500
Electric Skillet 1250
*Freezer 700
*Furnace Fan (3/5 HP) 875
*Garage Door Opener 500 to 750
Hair Dryer 1200

Device Running

Watts

Hand Drill 250 to 1100
Hedge Trimmer 450
Impact Wrench 500
Iron 1200
*Jet Pump 800
Lawn Mower 1200
Light Bulb 100
Microwave Oven 700 to 1000
*Milk Cooler 1100
Oil Burner on Furnace 300
Oil Fired Space Heater (140,000 Btu) 400
Oil Fired Space Heater (85,000 Btu) 225
Oil Fired Space Heater (30,000 Btu) 150
*Paint Sprayer, Airless (1/3 HP) 600
Paint Sprayer, Airless (handheld) 150
Radio 50 to 200
*Refrigerator 700
Slow Cooker 200
*Submersible Pump (1-1/2 HP) 2800
*Submersible Pump (1 HP) 2000
*Submersible Pump (1/2 HP) 1500
*Sump Pump 800 to 1050
*Table Saw (10") 1750 to 2000
Television 200 to 500
Toaster 1000 to 1650
Weed Trimmer 500

* Allow 3 times the listed watts for starting these devices.

Page 32

PART 3

ENGINE

TROUBLESHOOTING

GP Series Portable Generators

TABLE OF CONTENTS

PART TITLE PAGE#

3.1 389/206/163cc Troubleshooting
Flow Charts

3.2 410cc Troubleshooting Flow
Charts

3.3 Diagnostic Tests 42

34

37

Part 3 – Engine Troubleshooting .......................... 33

Section 3.1 – 389/206/163cc Troubleshooting

Flowcharts ....................................... 34

Section 3.2 – 410cc Troubleshooting Flowcharts .. 37

Section 3.3 – Diagnostic Tests .............................. 42

Test 20 – Check 1.5 Amp Fuse ........................42

Test 21 – Check Battery & Cables ...................42

Test 22 – Check Voltage at

Starter Contactor (SC) ........................42

Test 23 – Check Start-Run-Stop Switch ..........42

Test 24 – Test OFF-ON Switch .........................43

Test 25 – Check Starter Motor .........................43

Test 25 – Check Ignition Spark ........................45

Test 26 – Check Spark Plugs ...........................46

Test 29 – Check Carburetion ...........................46

Test 30 – Choke Test ........................................47

Test 33 – Check Valve Adjustment ...................47

Test 36 – Check Engine / Cylinder Leak Down

Test / Compression Test ......................48

Test 38 – Check Flywheel ................................48

Test 39 – Remove Wire 18 / Shutdown Lead ...49
Test 40 – Check / Adjust Governor

(389cc Engine) ....................................49

Test 41 – Check / Adjust Governor

(410cc Engine) ....................................50

Test 45 – Check Oil Level Switch .....................51

Test 46 – Check Oil Pressure Switch ...............51

Test 49 – Test Recoil Function .........................52

Test 50 – Test Engine Function ........................52

Page 33

SECTION 3.1

NOTHING

FOUND

FIX BAD COMPONENT

BAD

VISUALLY INSPECT FOR OBSTRUCTIONS
THAT WOULD CAUSE BINDING OF THE
RECOIL ONCE INSTALLED

AN INTERNAL ENGINE FAILURE HAS OCCURED.

VISUALLY INSPECT EXTERNAL
COMPONENTS FOR A FAILURE
THAT WOULD CAUSE THE
ENGINE TO BE SIEZED

REPLACE

BAD

BAD

GOOD GOOD

Problem 10 – Recoil Cord Will Not Pull

TEST 49 – TEST

RECOIL

FUNCTION

TEST 50 –

TEST ENGINE

FUNCTION

REPAIR

OR REPLACE

REPAIR

OR REPLACE

BAD

BAD

GOOD GOOD

GOOD

GOOD

TEST 26 –

CHECK
SPARK

CHECK FUEL

SUPPLY

CHECK CHOKE

POSITION AND

OPERATION

TEST 27 –

CHECK

SPARK PLUG

TEST 29 –

CHECK

CARBURETION

TEST 33 –
CHECK VALVE
ADJUSTMENT

CHECK FLYWHEEL KEY

TEST 36 – CHECK

ENGINE / CYLINDER

LEAK DOWN TEST /

COMPRESSION TEST

REPLACE SPARK PLUG

PUSH IN AFTER

STARTING

REPLENISH

FUEL

SUPPLY

REPLACE

REPLACE

MAGNETO

REPAIR OR REPLACE AS NECESSARY

REFER TO ENGINE SERVICE MANUAL

GOOD

GOOD

GOOD

GOOD

GOOD

ENGINE MISS

IS APPARENT

LOW FUEL

BAD

BAD

Problem 11 – Engine Starts Hard and Runs Rough

ADJUST VALVES

AND RETEST

BAD

BAD

TEST 40 – CHECK

AND ADJUST

GOVERNOR

TEST 38 – CHECK

FLYWHEEL

389/206/163cc TROUBLESHOOTING FLOW CHARTS

PART 3

ENGINE TROUBLESHOOTING

There are 4 different types of engines on the GP Series
generators: 410cc, 389cc, 206cc, 163cc. Section 3 is
divided into difference subsections that provide engine
troubleshooting for each type of engine. It is imperative
to identify what type of engine is used in order to effec­tively troubleshoot the problem.

The Specifications section at the front of this manual
provides details about engine displacement for the vari­ous GP Series generators.

389cc, 206cc and 163cc Engines, use Section 3.1

410cc Engine, use Section 3.2

Page 34

ENGINE TROUBLESHOOTING

ADJUST AND

RE-TEST

REPAIR

OR REPLACE

OFF

TURN

ON

GOOD

GOOD

SPARK

GOOD

GOOD

GOOD

GOOD

TEST 26 –

CHECK

SPARK

CHECK

FUEL

SUPPLY

CHECK FUEL

SHUTOFF

VALVE

TEST 27 –

CHECK SPARK

PLUG

TEST 38 –

CHECK

FLYWHEEL

TEST 29 –

CHECK

CARBURETION

TEST 33 –
CHECK VALVE
ADJUSTMENT

CHECK

FLYWHEEL

KEY

TEST 36 – CHECK ENGINE /

CYLINDER LEAK DOWN TEST /

COMPRESSION TEST

REPLENISH

FUEL

SUPPLY

REPLACE

FLYWHEEL

REPAIR OR REPLACE AS NECESSARY

REFER TO ENGINE SERVICE MANUAL

BAD

BAD

REPLACE

MAGNETO

GOOD

Problem 12 – Engine Turns Over But Will Not Start

TEST 39 – REMOVE

WIRE 18 /

SHUTDOWN LEAD

NO

SPARK

GOOD

BAD

BAD

BAD

BAD

REPLACE SWITCH

BAD

CHECK ENGINE

OIL LEVEL

TEST 45 –

CHECK OIL

LEVEL SWITCH

TEST 24 – TEST

OFF-ON SWITCH

REPLACE SWITCH

REPLENISH

OIL

REPLACE LOW OIL ALARM

GOOD

GOOD

OIL LEVEL O.K.

OIL LEVEL LOW

BAD

PART 3

389/206/163cc TROUBLESHOOTING FLOW CHARTS

SECTION 3.1

Page 35

SECTION 3.1

BAD

REPLACE

BAD

BAD

REPLACE

REPLACE MAGNETO

REPAIR OR

REPLACE

GOOD

GOOD

BAD

BAD - ENGINE

MISS APPARENT

GOOD

TEST 30 –

CHOKE TEST

TEST 26 –

CHECK

IGNTION

SPARK

TEST 27 – CHECK

SPARK PLUG

TEST 38 –

CHECK

FLYWHEEL

*Acceptable running limits for the engine are between 59-61 Hertz.

ADJUST / RE-TEST

TEST 33 –
CHECK VALVE
ADJUSTMENT

Problem 13 – Engine “Hunts” / Erratic Idle

NO

SURGING

STILL

SURGING

TEST 29 –

CHECK

CARBURETION

GOOD

TEST 40 – CHECK

AND ADJUST

GOVERNOR

389/206/163cc TROUBLESHOOTING FLOW CHARTS

PART 3

ENGINE TROUBLESHOOTING

Page 36

ENGINE TROUBLESHOOTING

RECHARGE OR REPLACE BATTERY

– CLEAN, REPAIR OR REPLACE

BAD CABLE(S)

BAD

REPLACE

BAD

GOOD

NO VOLTAGE

MEASURED

BAD

12 VDC

MEASURED

REPLACE STARTER

MOTOR IF DEFECTIVE

GOOD

CHECK FOR MECHANICAL BINDING
OF THE ENGINE OR ROTOR

Problem 20 – Engine Will Not Crank

TEST 21 – CHECK

BATTERY

& CABLES

TEST 23 – CHECK
START-RUN-STOP

SWITCH

TEST 25 – CHECK
STARTER MOTOR

TEST 22 – CHECK

VOLTAGE AT

STARTER

CONTACTOR

NOTHING

FOUND

FIX BAD COMPONENT

BAD

VISUALLY INSPECT FOR OBSTRUCTIONS
THAT WOULD CAUSE BINDING OF THE
RECOIL ONCE INSTALLED

AN INTERNAL ENGINE FAILURE HAS OCCURED.
POSSIBLE FAILURE COULD BE THE RESULT OF
A COMPRESSION RELEASE FAILURE. CONSULT
ENGINE SERVICE MANUAL P/N 0C1103A FOR
FURTHER ENGINE SERVICE INFORMATION.

VISUALLY INSPECT EXTERNAL
COMPONENTS FOR A FAILURE
THAT WOULD CAUSE THE
ENGINE TO BE SIEZED

REPLACE

BAD

BAD

GOOD GOOD

Problem 21 – Recoil Cord Will Not Pull (If So Equipped)

TEST 50 –

TEST ENGINE

FUNCTION

TEST 49 – TEST

RECOIL

FUNCTION

PART 3

SECTION 3.2

410cc TROUBLESHOOTING FLOW CHARTS

Page 37

SECTION 3.2

BAD

PULL OUT

ADJUST AND

RE-TEST

REPAIR

OR

REPLACE

REPLACE

REPLACE

OFF

TURN

ON

GOOD

GOOD

SPARK

GOOD

GOOD

GOOD

GOOD

GOOD

TEST 26 –

CHECK

SPARK

CHECK

FUEL

SUPPLY

CHECK FUEL

SHUTOFF

VALVE

PULL CHOKE

FULL OUT

TEST 23 – TEST

START-RUN-STOP

SWITCH

TEST 27 –

CHECK SPARK

PLUG

TEST 29 –

CHECK

CARBURETION

TEST 33 –
CHECK VALVE
ADJUSTMENT

TEST 36 – CHECK ENGINE /

CYLINDER LEAK DOWN TEST /

COMPRESSION TEST

REPLENISH

FUEL

SUPPLY

REPAIR OR REPLACE AS NECESSARY

REFER TO ENGINE SERVICE MANUAL

P/N 0C1103A FOR FURTHER ENGINE

SERVICE INFORMATION

BAD

Problem 22 – Engine Cranks But Will Not Start

TEST 39 – REMOVE

WIRE 18 /

SHUTDOWN LEAD

FULL OUT

NO

SPARK

BAD

GOOD

BAD

BAD

BAD

BAD

REPLACE

REPLACE MAGNETO

GO TO

“PROBLEM 24”

GOOD

TEST 38 –

CHECK

FLYWHEEL

TEST 38 –

CHECK

FLYWHEEL KEY

410cc TROUBLESHOOTING FLOW CHARTS

PART 3

DC CONTROL

Page 38

DC CONTROL

REPAIR

OR REPLACE

REPAIR

OR REPLACE

BAD

BAD

GOOD

GOOD

GOOD

TEST 26 –

CHECK

SPARK

CHECK FUEL

SUPPLY

CHECK CHOKE

POSITION AND

OPERATION

TEST 27 –

CHECK

SPARK PLUG

TEST 29 –

CHECK

CARBURETION

TEST 33 –

CHECK VALVE

ADJUSTMENT

CHECK FLYWHEEL KEY

TEST 36 – CHECK

ENGINE / CYLINDER

LEAK DOWN TEST /

COMPRESSION TEST

REPLACE SPARK PLUG

PUSH IN AFTER

STARTING

REPLENISH

FUEL

SUPPLY

REPAIR OR REPLACE AS NECESSARY

REFER TO ENGINE SERVICE MANUAL

P/N 0C1103A FOR FURTHER ENGINE

SERVICE INFORMATION

GOOD

GOOD

GOOD

GOOD

GOOD

ENGINE MISS
IS APPARENT

LOW FUEL

BAD

Problem 23 – Engine Starts Hard and Runs Rough

ADJUST VALVES

AND RETEST

BAD

BAD

TEST 41 – CHECK

AND ADJUST

GOVERNOR

BAD

REPLACE

REPLACE MAGNETO

GOOD

TEST 38 –

CHECK

FLYWHEEL

REPLACE SWITCH

REPLACE OIL

PRESSURE MODULE

BAD

TEST 46 – TEST OIL
PRESSURE SWITCH

TEST 23 – TEST

START-RUN-STOP

SWITCH

REPLACE SWITCH

REPLENISH

OIL

GOOD

GOOD

OIL LEVEL O.K.

OIL LEVEL LOW

BAD

Problem 24 – Engine Starts Then Shuts Down

CHECK ENGINE

OIL LEVEL

PART 3

SECTION 3.2

410cc TROUBLESHOOTING FLOW CHARTS

Page 39

SECTION 3.2

BAD

BAD

REPLACE

REPAIR OR

REPLACE

GOOD

GOOD

BAD

BAD - ENGINE

MISS APPARENT

GOOD

TEST 30 –

CHOKE TEST

TEST 26 –

CHECK

SPARK

TEST 27 – CHECK

SPARK PLUG

*Acceptable running limits for the engine are between 59-62 Hertz.

ADJUST / RE-TEST

TEST 33 –
CHECK VALVE
ADJUSTMENT

Problem 26 – Engine “Hunts” / Erratic Idle

NO

SURGING

STILL

SURGING

TEST 29 –

CHECK

CARBURETION

GOOD

TEST 41 – CHECK

AND ADJUST

GOVERNOR

BAD

REPLACE

REPLACE MAGNETO

GOOD

TEST 38 –

CHECK

FLYWHEEL

REPLACE

BAD

REPLACE FUSE

BAD

REPLACE
BATTERY

CHARGER

Problem 25 – Battery Will Not Charge

CHECK CONNECTIONS

ON BATTERY CHARGE

SOCKET

GOODGOOD

TEST 20 –

CHECK 1.5

AMP FUSE

410cc TROUBLESHOOTING FLOW CHARTS

PART 3

ENGINE TROUBLESHOOTING

Page 40

NOTES

Page 41

1A 1B1

WHT

STOP RUN START

0 GD 13A

TO MAGNETO

GROUND TO
STARTER CONTACTOR

SECTION 3.3

DIAGNOSTIC TESTS

PART 3

DC CONTROL

TEST 20 – CHECK 1.5 AMP FUSE

Figure 1. A Typical 1.5 Amp Fuse

DISCUSSION:
The fuse protects the wiring and the battery charger

from a short circuit.

PROCEDURE:
Push in on fuse holder cap and turn counterclockwise.

Then, remove the cap with fuse. Inspect the fuse.

RESULTS:
If the fuse element has melted open, replace the fuse

with an identical size fuse. If fuse is good, refer back
to flow chart.

TEST 21 – CHECK BATTERY & CABLES

PROCEDURE:
Inspect the battery cables and battery posts or termi-

nals for corrosion or tightness. Measure the voltage at
the terminal of the Starter Contactor and verify 11-12
volts DC is available to the generator during cranking.
If voltage is below 11 volts DC, measure at the battery
terminals during cranking. If battery voltage is below
11 volts DC, recharge/replace battery. If battery or
cables are still suspected, connect an alternate bat­tery and cables to the generator and retest.

TEST 22 – CHECK VOLTAGE AT STARTER

CONTACTOR (SC)

PROCEDURE:

1. Set voltmeter to measure DC voltage.

2. Disconnect Wire 16 from the Starter Contactor located
on the Starter motor.

3. Connect the positive meter test lead to Wire 16 previ­ously removed. Connect the negative meter test lead to
frame Ground.

4. Place the START-RUN-STOP Switch to START. 12 VDC
should be measured.

5. Reconnect Wire 16 to the Starter Motor.

RESULTS:
Refer back to flow chart.

TEST 23 – CHECK START-RUN-STOP SWITCH

DISCUSSION:
The START-RUN-STOP switch utilizes ground potential

to start and shutdown the engine. When the switch is
actuated to the START position a ground is applied to
the starter contactor where positive 12VDC is already
available allowing the engine to crank. Once the ground
is removed by putting the switch in the RUN posi­tion it disengages the starter allowing the engine to
operate normally. When the switch is actuated to the
STOP position a ground is applied to the magneto coils
grounding them out and inhibiting spark from occurring.

RESULTS:

1. Clean battery posts and cables as necessary. Make sure
battery cables are tight.

2. Recharge the battery, if necessary.

3. Replace the battery, if necessary.

4. If battery is good, but engine will not crank, refer back to
Flow Charts.

Page 42

Figure 2. START-RUN-STOP Switch

PROCEDURE:

1. Set a voltmeter to measure resistance.

2. Remove all wires from the START-RUN-STOP Switch
(SW1).

DC CONTROL

OFF

ON

OIL LEVEL ALARM

OFF-ON SWITCH

TO FRAME GROUND

TO FRAME GROUND

FROM OIL LEVEL SWITCH

TEST POINT A

MAGNETO

SHUTDOWN HARNESS

WIRE 18

00.01

PART 3

SECTION 3.3

DIAGNOSTIC TESTS

3. Connect one meter lead to Terminal 2 and connect the
other meter lead to Terminal 1. Actuate switch to the
START position. CONTINUITY should be measured.

4. Actuate switch to the STOP position. INFINITY should be
measured.

5. Keep one meter lead on Terminal 2 and connect the
other meter lead to Terminal 3. Actuate switch to the
STOP position. CONTINUITY should be measured.

6. Actuate switch to the START position. INFINITY should
be measured.

7. Connect one meter test lead to disconnected Wire 0
from Terminal 2 and connect the other meter test lead to
the positive post of the battery, 12 VDC should be mea­sured. If voltage is not measured, repair or replace Wire
13A between the starter contactor and the START-RUN­STOP switch.

8. Reconnect all wires to the switch.

RESULTS:

1. If anything but the readings above were measured
replace the START-RUN-STOP switch.

2. Refer back to flow chart.

TEST 24 – TEST OFF-ON SWITCH

DISCUSSION:
The OFF-ON switch applies a ground to the shutdown

harness (Wire 18). By applying a ground to the har­ness it grounds out the magneto and inhibits spark.

PROCEDURE:

1. Disconnect Point A from the switch harness (see Figure 3).

2. Connect one meter lead to the female side of the con­nector and connect other meter test lead to a clean
frame ground.

3. Actuate the switch back and for th between ON and
OFF. CONTINUITY should only be measure in the OFF
position.

RESULTS:

1. If switch failed Step 3, replace the OFF-ON switch.

2. If OFF-ON switch is good, refer back to flow chart.

TEST 25 – CHECK STARTER MOTOR

The following conditions can affect starter motor performance:

1. A binding or seizing condition in the Starter Motor bearings.

2. A shorted, open or grounded armature.

a. Shorted, armature (wire insulation worn and

wires touching one another). Will be indicated
by low or no RPM.

b. Open armature (wire broken) will be indicated

by low or no RPM and excessive current draw.

c. Grounded armature (wire insulation worn and wire

touching armature lamination or shaft). Will be
indicated by excessive current draw or no RPM.

3. A defective Starter Motor switch.

4. Broken, damaged or weak magnets.

5. Starter drive dirty or binding.

Figure 3. OFF-ON Switch Test Points (389cc Engine)

Page 43

STARTER

PINION

SECTION 3.3

DIAGNOSTIC TESTS

PROCEDURE:
The battery should have been checked prior to this

test and should be fully charged.

Set a voltmeter to measure DC voltage (12 VDC).
Connect the meter positive (+) test lead to the Starter
Contactor stud which has the small jumper wire con­nected to the Starter. Connect the common (-) test
lead to the Starter Motor frame.

Set the Star t-Stop Switch to its START position and
observe the meter. Meter should Indicate battery voltage,
Starter Motor should operate and engine should crank.

RESULTS:

1. If battery voltage is indicated on the meter but Starter
Motor did not operate, remove and bench test the
Starter Motor (see following test).

2. If battery voltage was indicated and the Starter Motor
tried to engage (pinion engaged), but engine did not
crank, check for mechanical binding of the engine or
rotor.

NOTE: If a starting problem is encountered, the
engine itself should be thoroughly checked to
eliminate it as the cause of starting difficulty. It is
a good practice to check the engine for freedom
of rotation by removing the spark plugs and turn­ing the crankshaft over slowly by hand, to be sure
it rotates freely.

PART 3

Figure 5. Check Pinion Gear Operation

TOOLS FOR STARTER PERFORMANCE TEST:
The following equipment may be used to complete a

performance test of the Starter Motor:

• Aclamp-onammeter.

• Atachometercapableofreadingupto10,000rpm.

•Afullycharged12voltbattery.

MEASURING CURRENT:
To read the current flow, in AMPERES, a clamp-on

ammeter may be used. This type of meter indicates
current flow through a conductor by measuring the
strength of the magnetic field around that conductor.

DC CONTROL

WARNING!: DO NOT ROTATE ENGINE WITH

ELECTRIC STARTER WITH SPARK PLUGS

*

REMOVED. ARCING AT THE SPARK PLUG
ENDS MAY IGNITE THE GASOLINE VAPOR
EXITING THE SPARK PLUG HOLE.

Figure 4. Starter Motor (SM)

CHECKING THE PINION:
When the Starter Motor is activated, the pinion gear

should move and engage the flywheel ring gear. If the
pinion does not move normally, inspect the pinion for
binding or sticking.

Figure 6. Clamp-On Ammeter

TACHOMETER:
A tachometer is available from your Generac Power

Systems source of supply. Order as P/N 042223. The
tachometer measures from 800 to 50,000 RPM (see
Figure 7).

Page 44

METAL STOCK
1/4" THICK STEEL

12"

1.0"

4"

2"

2.625"

3.5"

0.5"

0.5"

DRILL TWO HOLES — 1/2"
FOR STARTER
MOUNTING BRACKET

DRILL TWO HOLES — 1/2"
FOR MOUNTING TACHOMETER
TAP FOR 1/4-20 NC SCREWS

STARTER

CONTACTOR

STARTER

MOTOR

TA CHOMETER

12 VOLT

BATTERY

CLAMP ON

AMP METER

VISE

DC CONTROL

Figure 7. Tachometer

PART 3

SECTION 3.3

DIAGNOSTIC TESTS

Figure 8. Test Bracket Dimensions

TEST BRACKET:
A starter motor test bracket may be made as shown in

Figure 8.

REMOVE STARTER MOTOR:
It is recommended that the Starter Motor be removed

from the engine when testing Starter Motor perfor­mance. Assemble starter to test bracket and clamp
test bracket in vise (Figure 9).

TESTING STARTER MOTOR:

1. A fully charged 12 volt battery is required.

2. Connect jumper cables and clamp-on ammeter as
shown in Figure 9.

3. With the Starter Motor activated (jump the terminal on the
Starter Contactor to battery voltage), note the reading on
the clamp-on ammeter and on the tachometer (rpm).

Figure 9. Testing Starter Motor Performance

Note: Take the reading after the ammeter and
tachometer are stabilized , approximately 2-4
seconds.

4. A starter motor in good condition will be within the fol­lowing specifications:

Minimum rpm 4500

Maximum Amps 50

Note: Nominal amp draw of starter in generator is
60 amps.

TEST 25 – CHECK IGNITION SPARK

PROCEDURE:
A commercially available spark tester may be used

to test the engine ignition system. One can also be
purchased from Generac Power Systems (Part No.
0C5969).

1. Disconnect the spark plug lead from a spark plug.

2. Attach the high tension lead to the spark tester terminal.

3. Ground the spark tester clamp by attaching to the cylin­der head (see Figure 10).

Page 45

SPARK TESTER CLAMP
GROUNDED TO
CYLINDER HEAD

SPARK TESTER

SPARK PLUG
BOOT

SPARK TESTER CLAMP
CONNECTED TO
SPARK PLUG

SPARK TESTER

SPARK PLUG
BOOT

NORMAL MISFIRES

PRE-IGNITION DETONATION

SECTION 3.3

DIAGNOSTIC TESTS

Figure 10. Testing Ignition System

PART 3

DC CONTROL

Figure 12. Setting Spark Plug Gap

Figure 11. Checking Engine Miss

4. Crank the engine rapidly. Engine must be cranking at
350 rpm or more. If spark jumps the tester gap, you may
assume the ignition system is working properly. Repeat
on remaining cylinder spark plug.

5. If spark jumps the tester gap intermittently, the problem
may be in the Ignition Magneto.

RESULTS:
Refer back to the Flow Chart

PROCEDURE:
Remove spark plugs. Clean with a commercial solvent.

DO NOT BLAST CLEAN SPARK PLUGS. Replace
spark plugs if badly fouled, if ceramic is cracked, or
if badly worn or damaged. Refer to specifications in
the front of this manual for proper replacement spark
plugs and spark plug gaps.

Page 46

TEST 26 – CHECK SPARK PLUGS

Figure 13. Spark Plug Conditions

RESULTS:

1. Clean and regap or replace sparks plug as necessary.

2. Refer back to the Flow Chart.

TEST 29 – CHECK CARBURETION

PROCEDURE:
Before making a carburetion check, be sure the fuel sup-

ply tank has an ample supply of fresh, clean gasoline.
Check that all shutoff valves are open and fuel flows

freely through the fuel line.
Make sure the choke operates properly.
If the engine will not start, remove and inspect the spark

plug. If the spark plug is wet, look for the following:

• Overchoking.

• Excessivelyrichfuelmixture.

FEELER GAUGE

ALLEN WRENCH

DC CONTROL

PART 3

SECTION 3.3

DIAGNOSTIC TESTS

• Waterinfuel.

• Intakevalvestuckopen.

• Needle/floatstuckopen.

If the spark plug is dry look for the following:

• Leakingcarburetormountinggaskets.

• Intakevalvestuckclosed.

• Inoperativefuelpump.

• Pluggedfuelfilter(s).

• Varnishedcarburetor

If the engine starts hard or will not start, look for the
following:

• Physicaldamage tothe AC generator. Checkthe

Rotor for contact with the Stator.

• Startingunderload.Makesureallloadsarediscon­nected or turned off before attempting to crank and
start the engine.

• Checkthatthechokeisworkingproperly.

1. Remove fuel line at carburetor and ensure that there is

an adequate amount of fuel entering the carburetor.

2. Remove the float bowl and check to see if there is any

foreign matter in bottom of carburetor bowl.

3. The float is plastic and can be removed for access to the

needle so it can be cleaned.

TEST 33 – CHECK VALVE ADJUSTMENT

ADJUSTING VALVE CLEARANCE:
Improperly adjusted valves can cause various engine

related problems including, but not limited to, hard starting,
rough running and lack of power.

Adjust valve clearance with the engine at room tem­perature. The piston should be at top dead center
(TDC) of its compression stroke (both valves closed).

An alternative method is to turn the engine over and
position the intake valve fully open (intake valve spring
compressed) and adjust the exhaust valve clearance.
Turn the engine over and position the exhaust valve
fully open (exhaust valve spring compressed) and
adjust the intake valve clearance.

Correct valve clearance is given below.

Engine Intake Valve Exhaust Valve

189/206cc

389cc

410cc

0.0039 inch 0.0059 inch

0.006 ±0.0008 inch 0.006 ±0.0008 inch

0.003-0.005 inch 0.003-0.005 inch

4. With all of this removed, carburetor cleaner can be used

to clean the rest of the carburetor before reassembly.

5. After cleaning the carburetor with an approved carbure-

tor cleaner, blow dry with compressed air and reas­semble.

Shelf life on gasoline is 30 days. Proper procedures
need to be taken for carburetors so that the fuel doesn’t
varnish over time. A fuel stabilizer must be used at all
times in order to ensure that the fuel is fresh at all times.

RESULTS:
If carburetor is varnished, clean or replace. Refer to

back to Flow Chart.

TEST 30 – CHOKE TEST

PROCEDURE:
If the generator is surging it may have a carburetion

problem. A lean condition can cause erratic RPM.
Slowly pull the choke out to see if surging stops. If it
does stop, carburetion should be checked.

Figure 14. Adjusting Valve Clearance

1. Loosen the rocker arm jam nut. Turn the pivot ball stud
while checking the clearance between the rocker arm
and valve stem with a feeler gauge (see Figure 14).

2. When clearance is correct, hold the pivot ball stud with
the allen wrench and tighten the rocker arm jam nut to
the specified torque with a crow's foot. After tightening
the jam nut, recheck valve clearance to make sure it did
not change.

Rocker Arm Jam Nut ft-lbs

189cc 7.48

206cc 7.48

389cc 9-12

410cc 14.01

Page 47

CROW'S FOOT

SECTION 3.3

DIAGNOSTIC TESTS

INSTALL ROCKER ARM COVER

1. Use a new rocker arm cover gasket. Install the rocker
arm cover and retain with four screws.

RESULTS:
Adjust valves to specification and retest. If problem

continues, refer to Flow Chart.

TEST 36 – CHECK ENGINE / CYLINDER LEAK

DISCUSSION:
Most engine problems may be classified as one or a

combination of the following:

• Willnotstart.

• Startshard.

• Lackofpower.

• Runsrough.

• Vibration.

• Overheating.

• Highoilconsumption.

DISCUSSION:
The Cylinder Leak Down Tester checks the sealing

(compression) ability of the engine by measuring air
leakage from the combustion chamber. Compression
loss can present many different symptoms. This test
is designed to detect the section of the engine where
the fault lies before disassembling the engine.

PROCEDURE:

1. Remove the spark plug.

2. Gain access to the flywheel. Remove the valve cover.

3. Rotate the engine crankshaft until the piston reaches top
dead center (TDC). Both valves should be closed.

Figure 15. Tightening the Jam Nut

DOWN TEST / COMPRESSION TEST

PART 3

DC CONTROL

4. Lock the flywheel at top dead center.

5. Attach cylinder leak down tester adapter to spark plug
hole.

6. Connect an air source of at least 90 psi to the leak down
tester.

7. Adjust the regulated pressure on the gauge to 80 psi.

8. Read the right hand gauge on the tester for cylinder
pressure. 20 percent leakage is normally acceptable.
Use good judgement, and listen for air escaping at the
carburetor, the exhaust, and the crankcase breather.
This will determine where the fault lies.

RESULTS:

• Airescapesatthecarburetor–checkintakevalve.

• Airescapesthroughtheexhaust–checkexhaustvalve.

• Airescapesthroughthebreather–checkpistonrings.

• Airescapesfromthecylinderhead–theheadgas-

ket should be replaced.

CHECK COMPRESSION:
To check engine compression, remove the spark plug.

Insert an automotive type compression gauge into
the spark plug hole. Crank the engine until there is
no further increase in pressure. The highest reading
obtained is the engine compression pressure.

M I N I M U M A L L O WA B L E C O M P R E S S I O N
PRESSURE COLD ENGINE – 60 psi

If compression is poor, look for one or more of the fol­lowing causes:

• Loosecylinderheadbolts.

• Failedcylinderheadgasket.

• Burnedvalvesorvalveseats.

• Insufficientvalveclearance.

• Warpedcylinderhead.

• Warpedvalvestem.

• Wornorbrokenpistonring(s).

• Wornordamagedcylinderbore.

• Brokenconnectingrod.

• Wornvalveseatsorvalves.

• Wornvalveguides.

NOTE: Refer to Engine Service Manual Part
Number 0C1103A for further engine service infor­mation on the 410cc engine.

TEST 38 – CHECK FLYWHEEL

DISCUSSION:
In Test 25, a spark tester was used to check for

engine ignition. If sparking or weak spark occurred,
one possible cause might be the ignition magneto.
This test will check the magnetism of the flywheel and
will check the flywheel key.

Page 48

SPARK PLUG

ENGINE WIRE HARNESS

REMOVE LEAD

FLYWHEEL KEY

WIRE 18 TO

START-RUN-STOP SWITCH

(SHUTDOWN LEAD)

WIRE 18
CONNECTION

OFF

ON

OFF-ON SWITCH

MAGNETO

SHUTDOWN HARNESS

WIRE 18

DC CONTROL

PART 3

Figure 16. Engine Ground Harness

SECTION 3.3

DIAGNOSTIC TESTS

2. Remove the flywheel cover so that the magneto is
exposed.

3. Disconnect Wire 18 from the magneto.

4. Repeat Test 25, “Check Ignition Spark.”

RESULTS:

1. If spark now occurs, Wire 18 has a short to ground.
Trace Wire 18 back to the START-RUN-STOP switch
and Oil Pressure Module (If so equipped).

2. If spark still does not occur, refer back to flow chart.

PROCEDURE:

1. Check the flywheel magnet by holding a screwdriver at
the extreme end of its handle and with its point down.
When the tip of the screwdriver is moved to within 3/4
inch (19mm) of the magnet, the blade should be pulled
in against the magnet.

2. For rough running or hard starting engines check the fly­wheel key. The flywheel’s taper is locked on the crankshaft
taper by the torque of the flywheel nut. A keyway is pro­vided for alignment only and theoretically carries no load

Note: If the flywheel key becomes sheared or even
partially sheared, ignition timing can change.
Incorrect timing can result in hard starting or fail­ure to start.

TEST 39 – REMOVE WIRE 18 / SHUTDOWN

LEAD

DISCUSSION:
Wire 18 on all engines is used to shutdown the unit

when either the switch is placed in the OFF posi-

tion or a low oil condition has occurred. A ground
is applied to the magneto in both instances which
will inhibit spark and shutdown the unit. If a short to
ground exists on this wire the engine will be inhibited
from producing spark. This test will check the integrity
of the wire.

Note: The shutdown lead on units with the 389cc
engine will not be identified as Wire 18. Refer to
Figure 18 for identification of location.

PROCEDURE:

1. Turn off the fuel supply

Figure 17. Wire 18 (410cc Engine)

Figure 18. Shutdown Lead (389cc Engine)

TEST 40 – CHECK / ADJUST GOVERNOR

(389/206/163cc ENGINES)

INITIAL ADJUSTMENT:

1. Loosen the governor lever clamp bolt (See Figure

19).

2. While holding the governor lever in its full “INC. RPM”
position, rotate the governor shaft counter clockwise as
far as it will go.

Note: The governor shaft will only turn approx­imately 20 degrees from a full clockwise posi­tion. Do not apply excessive torque to the
governor shaft.

Page 49

SECTION 3.3

GOVERNOR SHAFT

GOVERNOR
CLAMP BOLT

GOVERNOR LEVER

APPLY

LOCTITE

HERE

SPEED ADJUST SCREW

INCREASE RPM

DIAGNOSTIC TESTS

PART 3

DC CONTROL

3. Tighten the governor lever clamp bolt to 110 inch­pounds.

RUNNING ADJUSTMENT:
After completing the initial adjustment, final adjust-

ment is accomplished with the engine running under
no-load.

1. Turn the speed adjustment screw counter clockwise
three full turns to avoid a possible engine overspeed
condition.

2. Start the engine and let it warm up and stabilize under
no-load.

3. Connect an AC frequency meter to one of the AC output
receptacles. No-load frequency should be between

62.0 - 62.5 hertz.

4. If the frequency/RPM are incorrect, turn the speed adjust
screw until frequency/RPM is within limits. Turn clock­wise to increase frequency/RPM, counter clockwise to
decrease the frequency/RPM (see Figure 19).

5. After adjustment is complete add a drop of removable
loctite (Loctite 241) to the threads of the speed adjust
screw (see Figure 19).

TEST 41 – CHECK / ADJUST GOVERNOR

(410cc ENGINE)

DISCUSSION:
The generator AC frequency output is directly pro-

portional to the speed of the rotor. A two-pole rotor
(having a single north and a single south magnetic
pole) will produce an AC frequency of 60 hertz at
3600 RPM.

The generator is equipped with a “voltage over fre­quency” type AC voltage regulator. The units AC out­put voltage is generally proportional to AC frequency.
A low or high governor speed will result in a corre­spondingly low or high AC frequency and voltage out­put. The governed speed must be adjusted before any
attempt to adjust the voltage regulator is made.

PROCEDURE

1. Loosen the governor clamp bolt (Figure 20).

2. Hold the governor lever at its wide open throttle position,
and rotate the governor shaft clockwise as far as it will
go. Then, tighten the governor lever clamp bolt to 70
inch-pounds (8 Nm).

3. Start the generator; let it stabilize and warm up at
no-load.

Page 50

Figure 19. Governor Adjustment Points (389cc Engine)

GOVERNOR

SHAFT

PRIMARY

ADJUST

SCREW

GOVERNOR

CLAMP

BOLT

LOW OIL SWITCH

DC CONTROL

Figure 20. Engine Governor Adjustment (410cc Engine)

PART 3

4. Connect a frequency meter across the generators AC
output leads.

SECTION 3.3

DIAGNOSTIC TESTS

3. Set VOM to measure resistance.

4. Connect one meter test lead to the previously discon­nect wire coming from the oil level switch. Connect the
other meter test lead to frame ground. INFINITY should
be measured.

RESULTS:

1. A reading of CONTINUITY indicates that the switch is no
longer functioning and will need to be replaced.

TEST 46 – CHECK OIL PRESSURE SWITCH

If the engine cranks and starts, then shuts down
almost immediately, the cause may be one or more of
the following:

• Lowengineoillevel.

• Lowoilpressure.

• Adefectiveoilpressureswitch.

5. Turn the primary adjust screw to obtain a frequency
reading of 62.5 Hz.

6. When frequency is correct at no load, check the AC volt­age reading. If voltage is incorrect, the voltage regulator
may require adjustment if so equipped.

RESULTS:

1. If, after adjusting the engine governor, frequency and
voltage are good, tests may be discontinued.

2. If frequency is now good, but voltage is high or low, refer
back to flow chart.

3. If engine was overspeeding, check linkage and throttle
for binding. If no governor response is indicated refer to
engine service manual.

4. If engine appears to run rough and results in low fre­quency, proceed to Problem 26 Flow Chart.

TEST 45 – CHECK OIL LEVEL SWITCH

DISCUSSION:
The 389cc engine does not utilize oil pressure to

lubricate the internal components. It utilizes a splash
type lubrication system. The switch should be nor­mally open as long as the engine is filled with oil. The
switch will close when the oil level drops to low the
switch will close and ground out the magnetos inhibit-

ing spark until the oil level is raised.

PROCEDURE:

1. Verify that the oil level is full.

2. Refer to Figure 3 in Section 3.3. Unplug the wire from
the oil level switch.

Figure 21. Low Oil Pressure Switch

PROCEDURE:

1. Check engine crankcase oil level.

a. Check engine oil level.
b. If necessary, add the recommended oil to

the dipstick FULL mark. DO NOT OVERFILL
ABOVE THE FULL MARK.

2. Do the following:

a. Disconnect Wire 86 and Wire 0 from the oil

pressure switch terminals. Remove the switch
and install an oil pressure gauge in its place.

b. Start the engine while observing the oil pres-

sure reading on gauge.

c. Note the oil pressure.

(1) Normal oil pressure is approximately 35-40

psi with engine running. If normal oil pres­sure is indicated, go to Step 4 of this test.

Page 51

SECTION 3.3

DIAGNOSTIC TESTS

PART 3

DC CONTROL

(2) If oil pressure is below about 10 psi, shut

engine down immediately. A problem exists
in the engine lubrication system. Refer to
Service Manual, Generac P/N 0F6923 for
engine service recommendations.

Note: The oil pressure switch is rated at 10 psi for
single cylinder engines.

3. Remove the oil pressure gauge and reinstall the oil pres­sure switch. Do NOT connect Wire 86 or Wire 0 to the
switch terminals.

a. Set a voltmeter to measure resistance.
b. Connect the meter test leads across the switch

terminals. With engine shut down, the meter
should read CONTINUITY.

c. Crank and start the engine. The meter should

read INFINITY.

d. Connect one test lead to Wire 0 ( disconnected from

LOP). Connect the other test lead to a clean frame
ground. CONTINUITY should be measured. If CON­TINUITY is NOT measured repair or replace Wire 0
between the LOP and the ground terminal connec­tion on the engine mount.

4. If the LOP switch tests good in Step 3 and oil pressure is
good in Step 2, but the unit still shuts down with a LOP
fault, check all wiring connections between the START­STOP-RUN switch and the LOP pressure module and
the LOP sender for a short to ground. Any ground on
this wire will cause Wire 18 to receive a ground also
inhibiting spark from occurring. If a short to ground is
found replace the respective wire.

RESULTS:

1. If LOP switch, oil pressure and wiring all test good, refer
back to flow chart.

2. If the LOP switch failed, replace the switch.

3. If no pressure was measured, an internal failure of the
oil pump may have occurred.

TEST 49 – TEST RECOIL FUNCTION

PROCEDURE:

1. Attempt to pull start the engine and make the following
observations while doing so.

a. Does the cord pull easily and smoothly?
b. Does the cord return with no assistance?
c. Does the engine tur n over as the cord is

pulled?

RESULTS:
If the recoil did not perform as the observations are

stated above, possible problems that could be present
are:

• Onthe410ccenginethecompressionreleasevalve

could be broken.

• Theenginecouldbeseized.

• The recoilcould have becomedetached from the

flywheel.

• The recoil mechanism could be broken and not to

properly retracting back into the engine.

TEST 50 – TEST ENGINE FUNCTION

PROCEDURE:

1. Remove the recoil and front cover assembly.

2. Remove the spark plug from the unit.

3. Attempt to turn the engine over by hand.

RESULTS:

1. If the engine can not turn over freely with the spark plug
removed, the engine has suffered some type of internal
failure that has seized it and is inhibiting it from running.

2. Refer back to flow chart.

Page 52

PART 4

DISASSEMBLY

GP Series Portable Generators

TABLE OF CONTENTS

PART TITLE

4.1. Major Disassembly

Page 53

SECTION 4.1

1

2

3

4

5

6

PART 4

DISASSEMBLY

MAJOR DISASSEMBLY

MAJOR DISASSEMBLY

DISCUSSION.
Each generator will have its own unique method of disassembly. Provided is a simplified version of disassembly

that does not go into step by step instructions. The figure below represents the basic disassembly and sequence
of steps needed to remove the fuel tank, stator, rotor, and the engine. All of the GP series generators have these
major components and the order of disassembly would not change.

An exploded view of each GP Series generator model is provided on the following pages.

Figure 1. Basic Disassembly Steps

Page 54

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

Page 55

SECTION 4.1

MAJOR DISASSEMBLY

Exploded View – GP1800 – Drawing No. 0H0609-A

PART 4

DISASSEMBLY

Page 56

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

1 1 ENGINE, 196CC

2 1 RECOIL ASSEMBLY

3 1 CARBURETOR

4 1 AIR CLEANER COVER

5 1 AIR FILTER

6 3 CARBURETOR GASKET

7 1 SPARK PLUG BOOT

8 1 OIL LEVEL SENSOR

9 1 FRAME, 1800W

10 1 FUEL SHUTOFF VALVE

11 2 VIBRATION MOUNT, #1

12 2 VIBRATION MOUNT, #2

13 1 AVR

ITEM QTY. DESCRIPTION

14 1 BRUSH ASSEMBLY

15 1 SPARK ARRESTOR

16 1 MUFFLER ASSEMBLY

17 1 FUEL TANK ASSEMBLY

18 1 FUEL TANK CAP ASSEMBLY

19 1 CONTROL PANEL ASSEMBLY

20 1 ASSEMBLY, ALTERNATOR 1800W

Page 57

SECTION 4.1

PORTABLE KIT

MAJOR DISASSEMBLY

Exploded View – GP3250 – Drawing No. 0H0522-C

PART 4

DISASSEMBLY

Page 58

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

1 1 ENGINE, 208CC

2 1 RECOIL ASSEMBLY

3 1 CARBURETOR

4 1 AIR CLEANER COVER

5 1 AIR FILTER

6 3 CARBURETOR GASKET

7 1 SPARK PLUG BOOT

8 1 OIL LEVEL SENSOR

9 1 FRAME, 3250W

10 1 FUEL SHUTOFF VALVE

11 2 VIBRATION MOUNT, #1

12 2 VIBRATION MOUNT, #2

13 1 AVR

ITEM QTY. DESCRIPTION

28 5 BOLT, FLANGE M6-1.0 X 40

29 2 BOLT, FLANGE M6-1.0 X 16

30 1 RUBBER GRIP, HANDLE 3250W

31 1 HANDLE, PORTABLE 3250W

32 1 ASSY, HANDLE BRACKET 3250W

33 1 ASSEMBLY, ALTERNATOR BRUSH

TYPE 3250W

14 1 BRUSH ASSEMBLY

15 1 SPARK ARRESTOR

16 1 MUFFLER ASSEMBLY

17 1 FUEL TANK ASSEMBLY

18 1 FUEL TANK CAP ASSEMBLY

19 1 CONTROL PANEL ASSEMBLY

20 2 WHEEL, 7” DIAMETER 3250W

21 2 WHEEL AXLE M12-1.75 THREADS

22 2 NUT, AXLE M12-1.75

23 2 WASHER, FLAT M12

24 2 COTTER PIN

25 2 BUMPER BRACKET 3250W

26 7 NUT, FLANGE M6-1.0

27 2 RUBBER BUMPER, 3250W

Page 59

SECTION 4.1

1

2

3

23

24

25

5

48

46

47

50

51

18

49

20

6

4

7

17

52

53

54

55

19

45

43

44

41

42

16

15

13

11

12

8

10

35

36

37

14

32

9

30

27

28

26

38

33

39

31

34

29

40

MAJOR DISASSEMBLY

Exploded View – GP5000 – Drawing No. 0G9384A-C

PART 4

DISASSEMBLY

Page 60

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

1 1 FRAME PARTS

2 1 ASSY CRADLE BASE

3 1 CRADLE END

4 1 PANEL RAIL

5 1 BACK RAIL

6 10

7 10

8 1 ENGINE/ALT PARTS

9 1 ENGINE, 389cc W/O MUFFLER

10 4

11 4 WASHER LOCK M8-5/16

12 4 SCREW HHC 5/16-18 x 1-1/4 G5

CURVED HEAD BOLT 5/16-18 x 1.625"
LONG
CAP NUT LOCKING 5/16-18, 5/16" OF
THREAD

VIB MOUNT RUBBER 1.38 x 1.0 x
5/16-18 MALE/FEMALE

ITEM QTY. DESCRIPTION

29 1 EXHAUST PARTS

30 1 BRACKET, MUFFLER SHIELD, BOTTOM

31 1 ASSY MUFFLER, 389cc

32 1 BRACKET, MUFFLER SHIELD TOP

33 1 GASKET, EXHUAST. 389cc

34 8 SCREW HHTT M6-1.0 x 12

35 4 WASHER FLAT 5/16-M8 ZINC

36 4 WASHER LOCK M8-5/16

37 4 SCREW HHC M8-1.25 x 12 G8.8 FT

38 2 STUD M8-125 x 35 G5 ZINC

39 2 HEX NUT M8-1.25 G8 CLEAR ZINC

40 4 SCREW HHC M6-1.0 x 16 C8.8

13 4 NUT LOCK FLG 5/16-18

14 1

15 1 SCROLL, ALTERNATOR, SKU

16 3 SCREW HHC M5-0.8 x 8 PC8.8

17 1 ELECTRICAL PARTS

18 1 ASSY RCP PANEL 30A RD NOHR MTR

19 1 ASSY POWER LEADS

20 4 SCREW PPPH #8-16 x 1/2" BZC

21 1 ASSY GND WIRE PNL TO ALT

22 1 ASSY GND WIRE ALT TO BASE

23 1 WASHER LOCK SPECIAL 1/4"

24 1 LUG SLDLSS #2-#8 x 17/64 CU

25 1 SCREW HHTT M6-1.0 x 25

ALTERNATOR 6500W METRIC TAPER
SHAFT

41 1 SPACER .34 x .62 x .590 ST/ZNC

42 1 SCREW HHC M8-1.25 x 30 C8.8

43 1 ACCESSORY KIT

44 1 ASSY HANDLE LH

45 4

46 2

47 1 ASSY HANDLE RH

48 2

49 2 SCREW HHFC 1/2-13 x 4.5 ZBC

50 2 NUT LOCK HEX 1/2-13 NYL INS

51 1 FRAME, BENT, FOOT BLACK 03

52 2 RUBBER FOOT

53 4 NUT LOCK FLG 5/16-18

CARRIAGE HEAD BOLT 5/16-18 x 1.75"
LONG
CAP NUT LOCKING 5/16-18, 5/16" OF
THREAD

TIRE 9.5" DIA RUN FLAT PLASTIC HUB/
RUBBER TREAD

26 1 FUEL TANK PARTS 6.6GL

27 1 FUEL TANK ASSY 6.6 GAL

28 4 SCREW HHTT M8-1.25 x 20

54 2 WASHER FLAT 5/16-M8 ZINC

55 2 SCREW HHC 5/16-18 x 1/2 G5

Page 61

SECTION 4.1

MAJOR DISASSEMBLY

Exploded View – GP5500 – Drawing No. 0H1253-A

PART 4

DISASSEMBLY

Page 62

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

2 1 ASSY CRADLE BASE

3 1 CRADLE END

3A 1 ASSEMBLY, FRAME 1 PIECE

4 1 PANEL RAIL

5 1 BACK RAIL

6 10 CURVED HEAD BOLT M8-1.25 X 42MM

7 11 CAP NUT LOCKING M8-1.25

9 1 ENGINE, 389cc W /0 MUFFLER

10 4

11 4 WASHER LOCK M8-5/16

12 4 SCREW HHC M8-1.25 X 30

13 8 NUT LOCK FLG M8-1.25

VIB MOUNT RUBBER 35MM X 25.4 X
M8-1.25

ITEM QTY. DESCRIPTION

25 1 SCREW HHTT M6-1.0 X 25

27 1 FUEL TANK ASSY 6.6 GAL PORTABLE

28 4 SCREW HHTT M8-1.25 X 20

29 1 FUEL CAP, VENTED

30 1 SHIELD, HEAT, SKU

31 1 BRACKET, MUFFLER 389CC

32 1 MUFFLER, 389CC

33 1 GASKET, EXHAUST 389CC

34 4 SCREW HHTT M6-1.0 X 12

35 4 WASHER FLAT 5/16-M8 ZINC

36 4 WASHER LOCK M8-5/16

37 4 SCREW HHC MB-1.25 X 20 G8.8 FT

14 2 WASHER FLAT 13mm

15 1 ALTERNATOR

15A * AVR

15B * BRUSH-ALTERNATOR

15C 1 SCROLL, ALTERNATOR, SKU

16 3 SCREW HHC M5-0.8 X 8 PC8.8

17 1 CLAMP HOSE .38-.87

18 1 FUEL HOSE, 4 ID, 8.5 OD X 120MM

20 4 SCREW PPPH #8-16 X 1/2" BZC

21 1 ASSY RCP PANEL 25A RD W/HR MTR

22 1 ASSY GND WIRE ALT TO BASE

23 1 WASHER LOCK SPECIAL 1/4"

24 1 LUG SLDLSS #2-#8 X 17/64 CU

38 2 STUD M8-1.25 X 35 G5 ZINC

39 2 HEX NUT M8-1.25 G8 CLEAR ZINC

44 1 ASSY HANDLE LH

45 4

47 1 ASSY HANDLE RH

48 2

49 2 AXLE PIN, 1/2" X 4", 3/4" HEAD

50 2 COTTER PIN, 1/8" X 1 1/4" ZN PLT

51 1 FRAME, BENT, FOOT

52 2 RUBBER FOOT, M8-1.25

54 2 WASHER FLAT 5/16-M8 ZINC

55 2 SCREW HHC M8-1.25 X 15

CA RRIAGE HEAD BOLT M8- 1.25 X
46mm LONG

TIRE 9,5" DIA RUN FLAT PLASTIC HUB/
RUBBER TREAD

Page 63

SECTION 4.1

1

2

3

23

24

25

5

48

46

47

50

51

18

49

20

6

4

7

17

52

53

19

45

43

44

41

42

16

15

13

11

12

8

10

35

36

37

14

32

9

30

27

28

26

38

33

39

31

34

29

40

MAJOR DISASSEMBLY

Exploded View – GP6500 – Drawing No. 0G9384B-C

PART 4

DISASSEMBLY

Page 64

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

1 1 FRAME PARTS

2 1 ASSY CRADLE BASE

3 1 CRADLE END

4 1 PANEL RAIL

5 1 BACK RAIL

6 10

7 10

8 1 ENGINE/ALT PARTS

9 1 ENGINE, 389cc W/O MUFFLER

10 4

11 4 WASHER LOCK M8-5/16

12 4 SCREW HHC 5/16-18 x 1-1/4 G5

CURVED HEAD BOLT 5/16-18 x 1.625"
LONG
CAP NUT LOCKING 5/16-18, 5/16" OF
THREAD

VIB MOUNT RUBBER 1.38 x 1.0 x
5/16-18 MALE/FEMALE

ITEM QTY. DESCRIPTION

28 4 SCREW HHTT M8-1.25 x 20

29 1 EXHAUST PARTS

30 1 BRACKET, MUFFLER SHIELD, BOTTOM

31 1 ASSY MUFFLER, 389cc

32 1 BRACKET, MUFFLER SHIELD TOP

33 1 GASKET, EXHUAST. 389cc

34 8 SCREW HHTT M6-1.0 x 12

35 4 WASHER FLAT 5/16-M8 ZINC

36 4 WASHER LOCK M8-5/16

37 4 SCREW HHC M8-1.25 x 12 G8.8 FT

38 2 STUD M8-125 x 35 G5 ZINC

39 2 HEX NUT M8-1.25 G8 CLEAR ZINC

13 4 NUT LOCK FLG 5/16-18

14 1

15 1 SCROLL, ALTERNATOR, SKU

16 3 SCREW HHC M5-0.8 x 8 PC8.8

17 1 ELECTRICAL PARTS

18 1 ASSY RCP PANEL 30A RD NOHR MTR

19 1 ASSY POWER LEADS

20 4 SCREW PPPH #8-16 x 1/2" BZC

21 1 ASSY GND WIRE PNL TO ALT

22 1 ASSY GND WIRE ALT TO BASE

23 1 WASHER LOCK SPECIAL 1/4"

24 1 LUG SLDLSS #2-#8 x 17/64 CU

25 1 SCREW HHTT M6-1.0 x 25

ALTERNATOR 6500W METRIC TAPER
SHAFT

40 4 SCREW HHC M6-1.0 x 16 C8.8

41 1 ACCESSORY KIT

42 1 ASSY HANDLE LH

43 4

44 2

45 1 ASSY HANDLE RH

46 2

47 2 SCREW HHFC 1/2-13 x 4.5 ZBC

48 2 NUT LOCK HEX 1/2-13 NYL INS

49 1 FRAME, BENT, FOOT BLACK 03

50 2 RUBBER FOOT

51 4 NUT LOCK FLG 5/16-18

52 2 WASHER FLAT 5/16-M8 ZINC

CARRIAGE HEAD BOLT 5/16-18 x 1.75"
LONG
CAP NUT LOCKING 5/16-18, 5/16" OF
THREAD

TIRE 9.5" DIA RUN FLAT PLASTIC HUB/
RUBBER TREAD

26 1 FUEL TANK PARTS 6.6GL

27 1 FUEL TANK ASSY 6.6 GAL

53 2 SCREW HHC 5/16-18 x 1/2 G5

Page 65

SECTION 4.1

MAJOR DISASSEMBLY

Exploded View – GP7000 – Drawing No. 0G9384D-B

PART 4

DISASSEMBLY

Page 66

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

1 1 CRADLE END

2 1 BACK RAIL

3 10

4 10

5 1 PANEL RAIL

6 1 ASSY CRADLE BASE

10 3 WASHER LOCK M8-5/16

11 3 SCREW HHC 3/8-16 x 1-1/4 G5

12 1 SCREW HHC 5/16-24 x 1-1/4 G5

13 2 SCREW HHC 5/16-18 x 1-1/4 G5

14 3 WASHER LOCK M10

15 8 NUT LOCK FLG 5/16-18

16 1 ALTERNATOR, 7000W

17 2

18 1 ENGINE, GH410

CURVED HEAD BOLT 5/16-18 x 1.625"
LONG

CAP NUT LOCKING 5/16-18 THREAD,
5/16" OF THREAD

VIB MOUNT RUBBER 1.38 x 1.0 x
5/16-18 MALE/FEMALE

ITEM QTY. DESCRIPTION

30 1 LUG SLDLSS #2-#8 X 17/64 CU

31 1 WASHER LOCK SPECIAL 1/4"

32 4 SCREW PPPH #8-16 x 1/2" BZC

33 1 ASSY GND WIRE ALT TO BASE

34 1

35 1 SCREW HHTT M6-1.0 x 25 BP

55 1 ACCESSORY KIT

56 1 ASSY HANDLE LH

57 4 CHB CUSTOM 5/16 18 x 46MM LONG

58 2

59 1 ASSY HANDLE RH

60 2

61 2 SCREW, HHC 1/2"-13 x 4-1/2" LONG

62 2

63 1 FRAME, BENT, FOOT

RECEPTACLE PANEL 30A RND W/HR
MTR

CAP NUT LOCKING 5/16-18, 5/16" OF
THREAD

TIRE 9.5" DIA RUN FLAT PLASTIC
HUB/RUBBER TREAD

NUT, LOCK HEX 1/2-13 NYLON
INSERT

19 1 BRACKET, MOUNT

20 2

21 2 WASHER LOCK M6-1/4

22 2 WASHER FLAT 5/16-M8 ZINC

23 2 WASHER FLAT 1/4-M6 ZINC

24 2 SCREW HHC 5/16-18 x 1-1/2 G5

25 2 SCREW HHC M6-1.0 x 16 C8,8

26 1 BRACKET, MOUNTING, MUFFLER 410

27 1

28 1 CAPACITOR, VOLTAGE REG VS

VIB MOUNT RUBBER 1.38 x 1.0 x
5/16-18 M/M

CLAMP HOSE .38-.87 [NOT SHOWN,
FUEL HOSE]

64 2 RUBBER FOOT

65 4 NUT LOCK FLG 5/16-18

66 2 WASHER FLAT 5/16-M8 ZINC

67 2 SCREW HHC 5/16-18 X 1/2 G5

68 1 FRAME, BENT, FOOT SUPPORT

69 2 WASHER FLAT 1/2 ZINC

70 4 SCREW HHTT M8-1.25 X 20

71 1 FUEL TANK ASSY 8.0 GAL PORTABLE

72 1 FUEL CAP-VENTED

Page 67

SECTION 4.1

MAJOR DISASSEMBLY

Exploded View – GP8000 – Drawing No. 0G9384F-B

PART 4

DISASSEMBLY

Page 68

DISASSEMBLY

PART 4

SECTION 4.1

MAJOR DISASSEMBLY

ITEM QTY. DESCRIPTION

1 1 CRADLE END

2 1 BACK RAIL

3 10

4 10

5 1 PANEL RAIL

6 1 ASSY CRADLE BASE

10 2 WASHER FLAT 5/16-M8 ZINC

11 2 NUT HEX LOCK M8-1.25 NY INS

12 2

13 4 NUT LOCK FLG 5/16-18

14 1 ASSEMBLY ENGINE GH-410

15 1 ALTERNATOR 8000W

16 2

17 2 WASHER LOCK M6-1/4

18 2 WASHER FLAT 1/4-M6 ZINC

19 2 SCREW HHC M6-1.0 x 16 C8.8

20 1 SCREW HHTR 5/16-18 x 3/4

21 1 BRACKET MUFFLER

22 4 SCREW FHSC 3/8-16 x 3/4

23 1

30 1 LUG SLDLSS #2-#8 x 17/64 CU

31 1 WASHER LOCK SPECIAL 1/4"

32 4 SCREW PPPH #8-16 x 1/2" BZC

33 1 ASSY GND WIRE ALT TO BASE

34 1 ASSY RCP PNL 8KW 30A W/HR MTR

35 1 SCREW HHTT M6-1.0 x 25 BP

55 1 ACCESSORY KIT

56 1 ASSY HANDLE LH

57 4 CHB CUSTOM 5/16 18 x 46MM LONG

58 2

59 1 ASSY HANDLE RH

CURVED HEAD BOLT 5/16-18 x 1.625"
LONG

CAP NUT LOCKING 5/16-18 THREAD)
5/16" OF THREAD

VIBE MOUNT 25.0 x 31.8 x M8-1.25
M/M

VIB MOUNT RUBBER 1.38 x 1.0 x
5/16-18 MALE/MALE

CLAMP HOSE .38-.87 [NOT SHOWN,
FUEL HOSE]

CAP NUT LOCKING 5/16-18, 5/16" OF
THREAD

ITEM QTY. DESCRIPTION

60 2

61 2 SCREW, HHC 1/2"-13 x 4-1/2" LONG

62 2

63 1 FRAME, BENT, FOOT

64 2 RUBBER FOOT

65 4 NUT LOCK FLG 5/16-18

66 2 WASHER FLAT 5/16-M8 ZINC

67 2 SCREW HHC 5/16-18 x 1/2 G5

68 1 FRAME) BENT, FOOT SUPPORT

69 2 WASHER FLAT 1/2 ZINC

70 4 SCREW HHTT M8-1.25 x 20

71 1 FUEL TANK ASSY 8.0 GAL

72 1 FUEL CAP-VENTED

75 1 BEARING CARRIER REAR

76 1 STATOR 8KW

77 1

78 I ROTOR ASSEMBLY, 8kW

79 I CAPACITOR

80 I CLAMP

81 5 WASHER LOCK M8-5/16

82 4 SCREW IHHC M8-1.25 x 140 G8.8

83 1 WASHER FLAT 5/16-M8 ZINC

84 1 SCREW IHHC 5/16-24 x 8-1/2 G5

85 1 COVER ALTERNATOR INLET

86 1 GROMMET WIRE SLEEVE

87 2 SCREW PPHM M4-0,7 x 10

88 4 WASHER FLAT #10 ZINC

89 4 WASHER LOCK #10

90 4 SCREW PPHM M5-0,8 x 30

91 1 SCREW HHTT M6-1.0 x 12

92 1

TIRE 9.5" DIA RUN FLAT PLASTIC
HUB/RUBBER TREAD

NUT, HEX LOCK 1-2"-13 NYLON
INSERT

(CASTING) ENGINE ADAPTER
HOUSING

ALTERNATOR FAN VARIED BLADE
SPACING

Page 69

SECTION 4.1

MAJOR DISASSEMBLY

PART 4

DISASSEMBLY

Page 70

PART 5

ELECTRICAL

DATA

GP Series Portable Generators

TABLE OF CONTENTS

DWG# TITLE PAGE

0H0612-A

0H0523-A

0G9769-C

0G9769-C

0G9849-A

0G9849-A

Electrical Schematic, GP1850 72

Electrical Schematic, GP3250

Electrical Schematic,

GP5000/5500/6500

Wiring Diagram,

GP5000/5500/6500

Electrical Schematic,

GP7000E/8000E

Wiring Diagram,

GP7000E/8000E

Electrical Formulas 78

73

74

75

76

77

Page 71

ELECTRICAL SCHEMATIC, GP1850

SENSING

DPE

Brushed Alternator Drawing No. 0H0612-A

PART 5

ELECTRICAL DATA

Page 72

ELECTRICAL DATA

SENSING

DPE

PART 5

ELECTRICAL SCHEMATIC, GP3250

Brushed Alternator Drawing No. 0H0523-A

Page 73

ELECTRICAL SCHEMATIC, GP5000/5500/6500

Brushed Alternator Drawing No. 0G9769-C

PART 5

ELECTRICAL DATA

Page 74

ELECTRICAL DATA

PART 5

WIRING DIAGRAM, GP5000/5500/6500

Brushed Alternator Drawing No. 0G9769-C

Page 75

ELECTRICAL SCHEMATIC, GP7000E/8000E



Brushless Alternator Drawing No. 0G9849-A

PART 5

ELECTRICAL DATA

Page 76

ELECTRICAL DATA



PART 5

WIRING DIAGRAM, GP7000E/8000E

Brushless Alternator Drawing No. 0G9849-A

Page 77

ELECTRICAL FORMULAS

TO FIND KNOWN VALUES 1-PHASE

KILOWATTS (kW)

KVA

AMPERES

WATTS

NO. OF ROTOR POLES

FREQUENCY

RPM

kW (required for Motor)

Volts, Current, Power Factor

Volts, Current

kW, Volts, Power Factor

Volts, Amps, Power Factor Volts x Amps

Frequency, RPM

RPM, No. of Rotor Poles

Frequency, No. of Rotor Poles

Motor Horsepower, Efficiency

E x I

1000

E x I

1000

kW x 1000

E

2 x 60 x Frequency

RPM

RPM x Poles

2 x 60

2 x 60 x Frequency

Rotor Poles

HP x 0.746

Efficiency

RESISTANCE

VOLTS

AMPERES

E = VOLTS I = AMPERES R = RESISTANCE (OHMS) PF = POWER FACTOR

Volts, Amperes

Ohm, Amperes I x R

Ohms, Volts

E

I

E

R

Page 78

NOTES

NOTES

Page 80

Part No. 0H0285 rev. A / Printed in USA 02.09
© 2009 Generac Power Systems, Inc. All rights reserved.

Generac Power Systems, Inc.

S45 W29290 Hwy. 59 • Waukesha, WI 53189

1-888-GENERAC (1-888-436-3722) • generac.com