Kohler ECV940, ECV980, Command PRO ECV940, Command PRO ECV980 Service Manual

ECV940 & ECV980

Service Manual

IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating

instruction of equipment that this engine powers.

Ensure engine is stopped and level before performing any maintenance or service.

2 Safety
3 Maintenance

5 Specifi cations
13 Tools and Aids
16 Troubleshooting
20 Air Cleaner/Intake
21 Electronic Fuel Injection (EFI) System
45 Governor System
55 Lubrication System
57 Electrical System
62 Starter System
66 Disassembly/Inspection and Service
83 Reassembly

62 690 05 Rev. -- 1

KohlerEngines.com

Safety

SAFETY PRECAUTIONS

WARNING: A hazard that could result in death, serious injury, or substantial property damage.

CAUTION: A hazard that could result in minor personal injury or property damage.

NOTE: is used to notify people of important installation, operation, or maintenance information.

WARNING

Explosive Fuel can cause
fi res and severe burns.

Do not fi ll fuel tank while
engine is hot or running.

Gasoline is extremely fl ammable
and its vapors can explode if
ignited. Store gasoline only in
approved containers, in well
ventilated, unoccupied buildings,
away from sparks or fl ames.
Spilled fuel could ignite if it comes
in contact with hot parts or sparks
from ignition. Never use gasoline
as a cleaning agent.

WARNING

Rotating Parts can cause
severe injury.

Stay away while engine
is in operation.

Keep hands, feet, hair, and
clothing away from all moving
parts to prevent injury. Never
operate engine with covers,
shrouds, or guards removed.

WARNING

Carbon Monoxide can
cause severe nausea,
fainting or death.

Avoid inhaling exhaust
fumes.

Engine exhaust gases contain
poisonous carbon monoxide.
Carbon monoxide is odorless,
colorless, and can cause death if
inhaled.

Accidental Starts can
cause severe injury or
death.

Disconnect and ground
spark plug lead(s) before
servicing.

Before working on engine or
equipment, disable engine as
follows: 1) Disconnect spark plug
lead(s). 2) Disconnect negative (–)
battery cable from battery.

Hot Parts can cause
severe burns.

Do not touch engine
while operating or just
after stopping.

Never operate engine with heat
shields or guards removed.

Cleaning Solvents can
cause severe injury or
death.

Use only in well
ventilated areas away
from ignition sources.

Carburetor cleaners and solvents
are extremely fl ammable. Follow
cleaner manufacturer’s warnings
and instructions on its proper and
safe use. Never use gasoline as a
cleaning agent.

Electrical Shock can
cause injury.

Do not touch wires while
engine is running.

WARNING

WARNING

WARNING

CAUTION

Damaging Crankshaft
and Flywheel can cause
personal injury.

Using improper procedures can
lead to broken fragments. Broken
fragments could be thrown from
engine. Always observe and use
precautions and procedures when
installing fl ywheel.

Failure to utilize or
reassemble debris
screen as designed could
result in debris screen
failure and serious
personal injury.

High Pressure Fluids can
puncture skin and cause
severe injury or death.

Do not work on fuel
system without proper
training or safety
equipment.

Fluid puncture injuries are highly
toxic and hazardous. If an injury
occurs, seek immediate medical
attention.

Explosive Fuel can
cause fi res and severe
burns.

Fuel system ALWAYS
remains under HIGH
PRESSURE.

Wrap a shop towel completely
around fuel pump module
connector. Press release button(s)
and slowly pull connector away
from fuel pump module allowing
shop towel to absorb any residual
fuel in high pressure fuel line. Any
spilled fuel must be completely
wiped up immediately.

CAUTION

CAUTION

WARNING

WARNING

2 62 690 05 Rev. --KohlerEngines.com

Maintenance

MAINTENANCE INSTRUCTIONS

WARNING

Accidental Starts can cause severe injury or
death.

Disconnect and ground spark plug lead(s)
before servicing.

Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair
establishment or individual; however, warranty repairs must be performed by a Kohler authorized dealer.

MAINTENANCE SCHEDULE

Every 100 Hours or Annually¹

● Change oil. Oil fi lter is recommended. Lubrication System

● Remove cooling shrouds and clean cooling areas. Air Cleaner/Intake

Every 150 Hours¹

● Check air cleaner element. Air Cleaner/Intake

● Replace unique Electronic Fuel Injection (EFI) fuel fi lter.

● Check oil cooler fi ns, clean as necessary. Lubrication System

Every 200 Hours

● Change oil fi lter. Lubrication System

Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.

Every 300 Hours

● Replace air cleaner element and check inner element. Air Cleaner/Intake

Every 600 Hours

● Replace air cleaner inner element. Air Cleaner/Intake

● Replace spark plugs and set gap. Electrical System

1

Perform these procedures more frequently under severe, dusty, dirty conditions.

REPAIRS/SERVICE PARTS

Kohler genuine service parts can be purchased from Kohler authorized dealers. To fi nd a local Kohler authorized
dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).

362 690 05 Rev. -- KohlerEngines.com

Maintenance

°F

-20

020324060

50 80 100

°C

-30 -20

-10 0

10 20 30

40

75

10W-30

5W-30

SAE 30

20W-50

OIL RECOMMENDATIONS

We recommend use of Kohler oils for best performance.
Other high-quality detergent oils (including synthetic)
of API (American Petroleum Institute) service class SJ
or higher are acceptable. Select viscosity based on
air temperature at time of operation as shown in table
below.

FUEL RECOMMENDATIONS

WARNING

Explosive Fuel can cause fi res and severe
burns.

Do not fi ll fuel tank while engine is hot or
running.

STORAGE

If engine will be out of service for 2 months or more
follow procedure below.

1. Add Kohler PRO Series fuel treatment or equivalent
to fuel tank. Run engine 2-3 minutes to get stabilized
fuel into fuel system (failures due to untreated fuel
are not warrantable).

2. Change oil while engine is still warm from operation.
Remove spark plug(s) and pour about 1 oz. of
engine oil into cylinder(s). Replace spark plug(s) and
crank engine slowly to distribute oil.

3. Disconnect negative (-) battery cable.

4. Store engine in a clean, dry place.

Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.

NOTE: E15, E20 and E85 are NOT approved and

should NOT be used; effects of old, stale or
contaminated fuel are not warrantable.

Fuel must meet these requirements:

● Clean, fresh, unleaded gasoline.

● Octane rating of 87 (R+M)/2 or higher.

● Research Octane Number (RON) 90 octane minimum.

● Gasoline up to 10% ethyl alcohol, 90% unleaded is

acceptable.

● Methyl Tertiary Butyl Ether (MTBE) and unleaded

gasoline blend (max 15% MTBE by volume) are
approved.

● Do not add oil to gasoline.

● Do not overfi ll fuel tank.

● Do not use gasoline older than 30 days.

4

62 690 05 Rev. --KohlerEngines.com

Engine Dimensions

484.61
[19.08]

Specifi cations

Dimensions in millimeters.

Inch equivalents shown in [ ].

152.50
[6.00]

50.00 [1.97]

22.50
[0.89]

FLYWHEEL SIDE

45˚

124.23 [4.89]

45˚
35˚

428.07
[16.85]

89.75
[3.53]

OIL

FILTER

MOUNTING

HOLE “A”

35˚

30.00
[1.18]

OIL FILL &
DIPSTICK

55˚

M8x1.25
4 STUD

45˚

325.25
[12.81]

20.01
[0.79]

62.70 [2.47]

2x Ø 35.00 [1.38]

45.00 [1.77]

406.25
[15.99]

MOUNTING

HOLE “A”

89.80
[3.54]

ENGINE MOUNTING
SURFACE

680.87
[26.81]

403.69
[15.89]

168.71 [6.64]
SPARK PLUG

STARTER SIDE

60.00 [2.36]

84.06 [3.31]

275.20
[10.83]

120.45

89.80

[4.74]

[3.54]

MOUNTING HOLE “A”

89.80

45˚

[3.54]

45˚

ENGINE MOUNTING SURFACE ( PTO END)

60.00 [2.36]

93.59 [3.68]

Ø 254.00 [10.00]

M8x1.25-6H

25.0 [0.98] DEEP

55˚

7 HOLES

EXHAUST PORT #1

18.00 [0.71]

OIL DRAIN PLUG
1/2 NPT INCH

MOUNTING

HOLE “A”

49.80
[1.96]

ENGINE MOUNTING SURFACE

OIL
PRESSURE
SWITCH

70.59 [2.78]

EXHAUST PORT #2

VALVE COVER SIDE

KohlerEngines.com

562 690 05 Rev. --

Specifi cations

ENGINE IDENTIFICATION NUMBERS

Kohler engine identifi cation numbers (model, specifi cation and serial) should be referenced for effi cient repair,
ordering correct parts, and engine replacement.

Model . . . . . . . . . . . . . . . . . . . . . ECV940

EFI Command Engine

Vertical Shaft

Numerical Designation

Specifi cation . . . . . . . . . . . . . . . ECV940-0001

Serial . . . . . . . . . . . . . . . . . . . . . 4323500328

Year Manufactured Code Factory Code
Code Year
43 2013
44 2014
45 2015

GENERAL SPECIFICATIONS

3,6

ECV940 ECV980

Bore 90 mm (3.54 in.)
Stroke 78.5 mm (3.1 in.)
Displacement 999 cc (61 cu. in.)
Oil Capacity (refi ll) 2.9 L (3.1 U.S. qt.)
Maximum Angle of Operation (@ full oil level)

TORQUE SPECIFICATIONS

3,5

4

ECV940 ECV980

25°

Blower Housing and Sheet Metal

M6 Screw
New, Untapped Hole (casting)
Used, Tapped Hole (casting)
New, Extruded Hole (sheet metal)
Used, Extruded Hole (sheet metal)
Mounting Clip (valley baffl e)

10.7 N·m (95 in. lb.)

7.3 N·m (65 in. lb.)

2.5 N·m (22 in. lb.)

2.0 N·m (18 in. lb.)

2.5 N·m (22 in. lb.)

Intake Manifold and Air Cleaner

Intake Manifold Mounting Fastener (torque in 2 increments) fi rst to 16.9 N·m (150 in. lb.)

fi nally to 22.6 N·m (200 in. lb.)
Air Cleaner Elbow to Throttle Body Mounting Nut 7.9 N·m (70 in. lb.)
Air Cleaner Bracket Mounting Screw (into intake manifold) 11.3 N·m (100 in. lb.)
GCU Bracket to Intake Manifold & Air Cleaner Bracket 11.3 N·m (100 in. lb.)
Ground Lead to Air Cleaner Bracket 5.6 N·m (50 in. lb.)
Fuel Injector Cap Fastener 7.3 N·m (65 in. lb.)
Manifold Absolute Pressure (MAP) Sensor Fastener 7.3 N·m (65 in. lb.)

Connecting Rod

Cap Fastener (torque in increments) 11.6 N·m (103 in. lb.)

3

Values are in Metric units. Values in parentheses are English equivalents.

4

Exceeding maximum angle of operation may cause engine damage from insuffi cient lubrication.

5

Lubricate threads with engine oil prior to assembly.

6

Any and all horsepower (hp) references by Kohler are Certifi ed Power Ratings and per SAE J1940 & J1995 hp

standards. Details on Certifi ed Power Ratings can be found at KohlerEngines.com.

6

62 690 05 Rev. --KohlerEngines.com

Specifi cations

TORQUE SPECIFICATIONS

3,5

ECV940 ECV980

Crankcase

Breather Cover Fastener 12.4 N·m (110 in. lb.)
Oil Drain Plug 21.4 N·m (16 ft. lb.)
Oil Temperature Sensor 7.3 N·m (65 in. lb.)
Dipstick Tube Screw 7.7 N·m (68 in. lb.)

Cylinder Head

Fastener (torque in 2 increments)
Head Bolt fi rst to 23.7 N·m (210 in. lb.)

fi nally to 46.9 N·m (415 in. lb.)
Pipe Plug 3/4 in. 28.5 N·m (252 in. lb.)
Rocker Arm Stud (AVT) 11.3 N·m (100 in. lb.)
Rocker Arm Screw (Non-AVT) 15.5 N·m (137 in. lb.)
Setscrew, AVT pivot locking 7.7 N·m (69 in. lb.)

Debris Screen

Hex Stud 21.5 N·m (190 in. lb.)
Mounting Screw - Hex Flange Screw 20.3 N·m (180 in. lb.)
Mounting Screw - Button Head Cap Screw 9.9 N·m (88 in. lb.)

Flywheel

Fan Fastener 10.4 N·m (92 in. lb.)
Retaining Screw 69.8 N·m (51 ft. lb.)

Fuel Pump

Module Baffl e to Crankcase Fastener 11.9 N·m (105 in. lb.)
Module to Baffl e Fastener 9.2 N·m (81 in. lb.)
Pulse Pump Screw (to blower housing) 2.8 N·m (25 in. lb.)

Governor (Electronic)

Governor Control Unit (GCU) to GCU Bracket 2.1 N·m (19 in. lb.)
Digital Linear Actuator (DLA) Bracket to GCU Bracket 10.2 N·m (90 in. lb.)
DLA to DLA Bracket Screw 7.3 N·m (65 in. lb.)

Governor (Mechanical)

Lever Nut 7.1 N·m (63 in. lb.)
Yoke Mounting Screw 2.2 N·m (20 in. lb.)

Ignition

Spark Plug 27 N·m (20 ft. lb.)
Coil Fastener 5.1 N·m (45 in. lb.)
Crankshaft Position Sensor Screw 11.3 N·m (100 in. lb.)
Crankshaft Position Sensor Bracket Screw 9.7 N·m (86 in. lb.)
Electronic Control Unit (ECU) to Bracket Screw 6.2 N·m (55 in. lb.)
Rectifi er-Regulator Fastener 2.5 N·m (22 in. lb.)

Lifter Feed Chamber Cover

Screw 6.6 N·m (58 in. lb.)

3

Values are in Metric units. Values in parentheses are English equivalents.

5

Lubricate threads with engine oil prior to assembly.

KohlerEngines.com

762 690 05 Rev. --

Specifi cations

TORQUE SPECIFICATIONS

3,5

ECV940 ECV980

Muffl er

Retaining Nut 24.4 N·m (216 in. lb.)
Screw, intermittent bracket (into weld nut) 13.6 N·m (120 in. lb.)
M6 Screw 9.9 N·m (88 in. lb.)
M8 Screw 24.4 N·m (216 in. lb.)

Oil Cooler

Mounting Screw 2.3 N·m (21 in. lb.)

Oil Filter Adapter/Housing

Mounting Screw 23.7 N·m (210 in. lb.)
Oil Filter Nipple 17.8 N·m (158 in. lb.)

Oil Pan

Fastener 25.6 N·m (227 in. lb.)
Oil Temperature Sensor 13.6 N·m (120 in. lb.)
Oil Temperature Sensor Reducer Bushing 17.6 N·m (156 in. lb.)
Oil Temperature Sensor Nut 2.3 N·m (20 in. lb.)

Oil Pickup Screen

Mounting Screw 11.3 N·m (100 in. lb.) into a new hole

7.7 N·m (68 in. lb.) into a used hole

Oil Pump

Mounting Screw 9.9 N·m (88 in. lb.)

Oil Sentry

TM

Pressure Switch 10.7 N·m (95 in. lb.)

Solenoid (starter)

Mounting Hardware 4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead 8.0-11.0 N·m (71-97 in. lb.)

Starter Assembly

Thru Bolt 5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw 16 N·m (142 in. lb.)
Brush Holder Mounting Screw 2.5-3.3 N·m (22-29 in. lb.)

Stator

Mounting Screw 9.3 N·m (82 in. lb.)

Throttle Control Bracket

Fastener 9.9 N·m (88 in. lb.)

Valve Cover

Fastener 13.6 N·m (120 in. lb.)

3

Values are in Metric units. Values in parentheses are English equivalents.

5

Lubricate threads with engine oil prior to assembly.

8

62 690 05 Rev. --KohlerEngines.com

Specifi cations

CLEARANCE SPECIFICATIONS

3

ECV940 ECV980

Camshaft

End Play 0.3/1.3 mm (0.011/0.051 in.)
Running Clearance 0.025/0.063 mm (0.0010/0.0025 in.)
Bore I.D.

New
Max. Wear Limit

20.000/20.025 mm (0.7874/0.7884 in.)

20.038 mm (0.7889 in.)

Bearing Surface O.D.
New
Max. Wear Limit

19.962/19.975 mm (0.7859/0.7864 in.)

19.959 mm (0.7858 in.)

Cam Lobe Profi le (minimum dimension, measured from base circle
to top of lobe)
Exhaust 35 mm (1.3779 in.)

Intake 34.1 mm (1.3425 in.) 35 mm (1.3779 in.)

Connecting Rod

Crankpin End I.D. @ 70°F
New
Max. Wear Limit

44.030/44.037 mm (1.7334/1.7337 in.)

0.070 mm (0.0028 in.)

Connecting Rod-to-Crankpin Running Clearance
New
Max. Wear Limit

0.030/0.055 mm (0.0012/0.0022 in.)

0.070 mm (0.0028 in.)
Connecting Rod-to-Crankpin Side Clearance 0.30/0.59 mm (0.0118/0.0232 in.)
Connecting Rod-to-Piston Pin Running Clearance 0.015/0.028 mm (0.0006/0.0011 in.)
Piston Pin End I.D. @ 70°F

New
Max. Wear Limit

19.015/19.023 mm (0.7486/0.7489 in.)

19.036 mm (0.7494 in.)

Crankcase

Governor Cross Shaft Bore I.D. (Mechanical Governor)
New
Max. Wear Limit

8.025/8.050 mm (0.3159/0.3169 in.)

8.088 mm (0.3184 in.)

Crankshaft

End Play (free) 0.30/1.50 mm (0.011/0.059 in.)
Bore (in crankcase)

New 45.043/45.068 mm (1.7733/1.7743 in.)
Crankshaft Bore (in crankcase)-to-Crankshaft Running Clearance

New 0.043/0.090 mm (0.0017/0.0035 in.)
Bore (in oil pan)

New, Without Bearing 50.025/50.00 mm (1.9694/1.9685 in.)
Crankshaft to Sleeve Bearing (in oil pan) Running Clearance

New 0.040/0.167 mm (0.0015/0.0065 in.)
Oil Pan End Main Bearing Journal

O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round

44.978/45.00 mm (1.770/1.771 in.)

44.90 mm (1.767 in.)

0.022 mm (0.0009 in.)

0.025 mm (0.0010 in.)
Connecting Rod Journal

O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
Width

43.982/44.000 mm (1.731/1.732 in.)

43.97 mm (1.731 in.)

0.018 mm (0.0007 in.)

0.025 mm (0.0010 in.)

53.00/53.09 mm (2.0866/2.0901 in.)

3

Values are in Metric units. Values in parentheses are English equivalents.

KohlerEngines.com

962 690 05 Rev. --

Specifi cations

CLEARANCE SPECIFICATIONS

3

ECV940 ECV980

Crankshaft Continued

T.I.R.
PTO End, Crank in Engine
Entire Crank, in V-Blocks

0.279 mm (0.0110 in.)

0.10 mm (0.0039 in.)

Flywheel End Main Bearing Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round

44.978/45.00 mm (1.770/1.771 in.)

44.90 mm (1.767 in.)

0.022 mm (0.0009 in.)

0.025 mm (0.0010 in.)

Crankshaft Bearing (PTO)

New (installed)
Max. Wear Limit

45.040/45.145 mm (1.773.1.777 in.)

45.158 mm

Cylinder Bore

I.D.
New
Max. Wear Limit
Max. Taper
Max. Out-of-Round

90.000/90.025 mm (3.543/3.544 in.)

90.075 mm (3.546 in.)

0.013 mm (0.00051 in.)

0.013 mm (0.00051 in.)

Cylinder Head

Max. Out-of-Flatness 0.076 mm (0.003 in.)

Governor (Mechanical)

Governor Cross Shaft-to-Crankcase Running Clearance 0.025/0.087 mm (0.0009/0.0034 in.)
Cross Shaft O.D.

New

7.963/8.000 mm (0.3135/.3149 in.)

7.936 mm (0.3124 in.)

Max. Wear Limit
Governor Gear Shaft-to-Governor Gear Running Clearance 0.070/0.160 mm (0.0027/0.0063 in.)
Gear Shaft O.D.

New
Max. Wear Limit

5.990/6.000 mm (0.2358/0.2362 in.)

5.977 mm (0.2353 in.)

Ignition

Spark Plug Gap 0.76 mm (0.030 in.)
Module Air Gap 0.28/0.33 mm (0.011/0.013 in.)

Piston, Piston Rings, and Piston Pin

Piston-to-Piston Pin Running Clearance 0.006/0.018 mm (0.0002/0.0007 in.)
Pin Bore I.D.

New
Max. Wear Limit

19.006/17.013 mm (0.7482/0.7485 in.)

19.025 mm (0.7490 in.)

Pin O.D.
New
Max. Wear Limit

18.995/19.000 mm (0.7478/0.7480 in.)

18.994 mm (0.7478 in.)
Top Compression Ring-to-Groove Side Clearance 0.04/0.08 mm (0.0015/0.0031 in.)
Middle Compression Ring-to-Groove Side Clearance 0.04/0.08 mm (0.0015/0.0031 in.)
Oil Control Ring-to-Groove Side Clearance 0.03/0.19 mm (0.0011/0.0074 in.)
Top and Center Compression Ring End Gap

New Bore
Used Bore (max.)

3

Values are in Metric units. Values in parentheses are English equivalents.

10

0.30/0.55 mm (0.011/0.021 in.)

0.94 mm (0.037 in.)

62 690 05 Rev. --KohlerEngines.com

Specifi cations

CLEARANCE SPECIFICATIONS

3

ECV940 ECV980

Piston, Piston Rings, and Piston Pin Continued

Thrust Face O.D.
New
Max. Wear Limit

7

89.953/89.967 mm (3.5414/3.5420 in.)

89.925 mm (3.540 in.)

Piston Thrust Face-to-Cylinder Bore7 Running Clearance
New 0.033/0.071 mm (0.0013/0.0028 in.)

Valves and Valve Lifters

Hydraulic Valve Lifter to Crankcase Running Clearance 0.012/0.050 mm (0.0004/0.0019 in.)
Intake Valve Stem-to-Valve Guide Running Clearance 0.038/0.076 mm (0.0015/0.0030 in.)
Exhaust Valve Stem-to-Valve Guide Running Clearance 0.050/0.088 mm (0.0020/0.0035 in.)
Intake Valve Guide I.D.

New
Max. Wear Limit

7.038/7.058 mm (0.2771/0.2779 in.)

7.135 mm (0.2809 in.)

Exhaust Valve Guide I.D.
New
Max. Wear Limit

7.038/7.058 mm (0.2771/0.2779 in.)

7.159 mm (0.2819 in.)

Guide Reamer Size
Standard

0.25 mm O.S.

7.048 mm (0.2775 in.)

7.298 mm (0.2873 in.)

Nominal Valve Face Angle 45°

3

Values are in Metric units. Values in parentheses are English equivalents.

7

Measure 11 mm (0.4331 in.) above bottom of piston skirt at right angles to piston pin.

KohlerEngines.com

1162 690 05 Rev. --

Specifi cations

GENERAL TORQUE VALUES

English Fastener Torque Recommendations for Standard Applications

Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel

Size Grade 2 Grade 5 Grade 8

Tightening Torque: N·m (in. lb.) ± 20%

8-32 2.3 (20) 2.8 (25) — 2.3 (20)
10-24 3.6 (32) 4.5 (40) — 3.6 (32)
10-32 3.6 (32) 4.5 (40) — —

1/4-20 7.9 (70) 13.0 (115) 18.7 (165) 7.9 (70)

1/4-28 9.6 (85) 15.8 (140) 22.6 (200) —
5/16-18 17.0 (150) 28.3 (250) 39.6 (350) 17.0 (150)
5/16-24 18.7 (165) 30.5 (270) — —

3/8-16 29.4 (260) — — —

3/8-24 33.9 (300) — — —

Tightening Torque: N·m (ft. lb.) ± 20%

5/16-24 — — 40.7 (30) —

3/8-16 — 47.5 (35) 67.8 (50) —

3/8-24 — 54.2 (40) 81.4 (60) —
7/16-14 47.5 (35) 74.6 (55) 108.5 (80) —
7/16-20 61.0 (45) 101.7 (75) 142.5 (105) —

1/2-13 67.8 (50) 108.5 (80) 155.9 (115) —

1/2-20 94.9 (70) 142.4 (105) 223.7 (165) —
9/16-12 101.7 (75) 169.5 (125) 237.3 (175) —
9/16-18 135.6 (100) 223.7 (165) 311.9 (230) —

5/8-11 149.5 (110) 244.1 (180) 352.6 (260) —

5/8-18 189.8 (140) 311.9 (230) 447.5 (330) —

3/4-10 199.3 (147) 332.2 (245) 474.6 (350) —

3/4-16 271.2 (200) 440.7 (325) 637.3 (470) —

Grade 2 or 5 Fasteners

Into Aluminum

Metric Fastener Torque Recommendations for Standard Applications

Size

4.8

5.8

Tightening Torque: N·m (in. lb.) ± 10%

M4 1.2 (11) 1.7 (15) 2.9 (26) 4.1 (36) 5.0 (44) 2.0 (18)
M5 2.5 (22) 3.2 (28) 5.8 (51) 8.1 (72) 9.7 (86) 4.0 (35)
M6 4.3 (38) 5.7 (50) 9.9 (88) 14.0 (124) 16.5 (146) 6.8 (60)
M8 10.5 (93) 13.6 (120) 24.4 (216) 33.9 (300) 40.7 (360) 17.0 (150)

Tightening Torque: N·m (ft. lb.) ± 10%

M10 21.7 (16) 27.1 (20) 47.5 (35) 66.4 (49) 81.4 (60) 33.9 (25)
M12 36.6 (27) 47.5 (35) 82.7 (61) 116.6 (86) 139.7 (103) 61.0 (45)
M14 58.3 (43) 76.4 (56) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)

12

Property Class

8.8

10.9 12.9

Torque Conversions

N·m = in. lb. x 0.113 in. lb. = N·m x 8.85

N·m = ft. lb. x 1.356 ft. lb. = N·m x 0.737

Noncritical

Fasteners

Into Aluminum

62 690 05 Rev. --KohlerEngines.com

Tools and Aids

Certain quality tools are designed to help you perform specifi c disassembly, repair, and reassembly procedures. By
using these tools, you can properly service engines easier, faster, and safer! In addition, you’ll increase your service
capabilities and customer satisfaction by decreasing engine downtime.

Here is a list of tools and their source.

SEPARATE TOOL SUPPLIERS

Kohler Tools
Contact your local Kohler source of
supply.

TOOLS

Description Source/Part No.

Alcohol Content Tester

For testing alcohol content (%) in reformulated/oxygenated fuels.

Camshaft Endplay Plate

For checking camshaft endplay.

Camshaft Seal Protector (Aegis)

For protecting seal during camshaft installation.

Cylinder Leakdown Tester

For checking combustion retention and if cylinder, piston, rings, or valves are worn.
Individual component available:
Adapter 12 mm x 14 mm (Required for leakdown test on XT-6 engines)

Dealer Tool Kit (Domestic)

Complete kit of Kohler required tools.
Components of 25 761 39-S
Ignition System Tester
Cylinder Leakdown Tester
Oil Pressure Test Kit
Rectifi er-Regulator Tester (120 V AC/60Hz)

Dealer Tool Kit (International)

Complete kit of Kohler required tools.
Components of 25 761 42-S
Ignition System Tester
Cylinder Leakdown Tester
Oil Pressure Test Kit
Rectifi er-Regulator Tester (240 V AC/50Hz)

Digital Vacuum/Pressure Tester

For checking crankcase vacuum.
Individual component available:
Rubber Adapter Plug

Electronic Fuel Injection (EFI) Diagnostic Software

For Laptop or Desktop PC.

EFI Service Kit

For troubleshooting and setting up an EFI engine.
Components of 24 761 01-S
Fuel Pressure Tester
Noid Light
90° Adapter
In-line "T" Fitting
Code Plug, Red Wire
Code Plug, Blue Wire
Shrader Valve Adapter Hose

Flywheel Holding Tool (CS)

For holding fl ywheel of CS series engines.

Flywheel Puller

For properly removing fl ywheel from engine.

Flywheel Strap Wrench

For holding fl ywheel during removal.

SE Tools
415 Howard St.
Lapeer, MI 48446
Phone [phone]
Toll Free 800-664-2981
Fax [phone]

Design Technology Inc.
768 Burr Oak Drive
Westmont, IL 60559
Phone [phone]
Fax [phone]

Kohler 25 455 11-S

SE Tools KLR-82405

SE Tools KLR-82417

Kohler 25 761 05-S

Design Technology Inc.

DTI-731-03

Kohler 25 761 39-S

Kohler 25 455 01-S
Kohler 25 761 05-S
Kohler 25 761 06-S
Kohler 25 761 20-S

Kohler 25 761 42-S

Kohler 25 455 01-S
Kohler 25 761 05-S
Kohler 25 761 06-S
Kohler 25 761 41-S

Design Technology Inc.

DTI-721-01

Design Technology Inc.

DTI-721-10

Kohler 25 761 23-S

Kohler 24 761 01-S

Design Technology Inc.

DTI-019
DTI-021
DTI-023
DTI-035
DTI-027
DTI-029
DTI-037

SE Tools KLR-82407

SE Tools KLR-82408

SE Tools KLR-82409

1362 690 05 Rev. -- KohlerEngines.com

Tools and Aids

TOOLS

Description Source/Part No.

Hydraulic Valve Lifter Tool

For removing and installing hydraulic lifters.

Ignition System Tester

For testing output on all systems, including CD.

Inductive Tachometer (Digital)

For checking operating speed (RPM) of an engine.

Offset Wrench (K and M Series)

For removing and reinstalling cylinder barrel retaining nuts.

Oil Pressure Test Kit

For testing/verifying oil pressure on pressure lubricated engines.

Radiator Tester

For pressure testing radiator and cap on Aegis liquid-cooled engines.

Rectifi er-Regulator Tester (120 volt current)
Rectifi er-Regulator Tester (240 volt current)

For testing rectifi er-regulators.
Components of 25 761 20-S and 25 761 41-S
CS-PRO Regulator Test Harness
Special Regulator Test Harness with Diode

Spark Advance Module (SAM) Tester

For testing SAM (ASAM and DSAM) on engines with SMART-SPARK

.

™

Starter Servicing Kit (All Starters)

For removing and reinstalling drive retaining rings and brushes.
Individual component available:
Starter Brush Holding Tool (Solenoid Shift)

Triad/OHC Timing Tool Set

For holding cam gears and crankshaft in timed position while installing timing belt.

Valve Guide Reamer (K and M Series)

For properly sizing valve guides after installation.

Valve Guide Reamer O.S. (Command Series)

For reaming worn valve guides to accept replacement oversize valves. Can be used
in low-speed drill press or with handle below for hand reaming.

Reamer Handle

For hand reaming using Kohler 25 455 12-S reamer.

Valve Guide Service Kit (Courage, Aegis, Command, OHC)

For servicing worn valve guides.

Kohler 25 761 38-S

Kohler 25 455 01-S

Design Technology Inc.

DTI-110

Kohler 52 455 04-S

Kohler 25 761 06-S

Kohler 25 455 10-S

Kohler 25 761 20-S
Kohler 25 761 41-S

Design Technology Inc.

DTI-031
DTI-033

Kohler 25 761 40-S

SE Tools KLR-82411

SE Tools KLR-82416

Kohler 28 761 01-S

Design Technology Inc.

DTI-K828

Kohler 25 455 12-S

Design Technology Inc.

DTI-K830

SE Tools KLR-82415

AIDS
Description Source/Part No.

Camshaft Lubricant (Valspar ZZ613) Kohler 25 357 14-S
Dielectric Grease (GE/Novaguard G661) Kohler 25 357 11-S
Dielectric Grease Loctite® 51360
Kohler Electric Starter Drive Lubricant (Inertia Drive) Kohler 52 357 01-S
Kohler Electric Starter Drive Lubricant (Solenoid Shift) Kohler 52 357 02-S
RTV Silicone Sealant

Loctite® 5900® Heavy Body in 4 oz. aerosol dispenser.
Only oxime-based, oil resistant RTV sealants, such as those listed, are approved

for use. Loctite® Nos. 5900® or 5910® are recommended for best sealing
characteristics.

Spline Drive Lubricant Kohler 25 357 12-S

14 62 690 05 Rev. --KohlerEngines.com

Kohler 25 597 07-S

Loctite® 5910

®

Loctite® Ultra Black 598™

Loctite® Ultra Blue 587™

Loctite® Ultra Copper 5920™

Tools and Aids

FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL

A fl ywheel holding tool can be made out of an old junk
fl ywheel ring gear and used in place of a strap wrench.

1. Using an abrasive cut-off wheel, cut out a six tooth
segment of ring gear as shown.

2. Grind off any burrs or sharp edges.

3. Invert segment and place it between ignition bosses
on crankcase so tool teeth engage fl ywheel ring
gear teeth. Bosses will lock tool and fl ywheel in
position for loosening, tightening, or removing with a
puller.

A spanner wrench to lift rocker arms or turn crankshaft
may be made out of an old junk connecting rod.

1. Find a used connecting rod from a 10 HP or larger
engine. Remove and discard rod cap.

2. Remove studs of a Posi-Lock rod or grind off
aligning steps of a Command rod, so joint surface is
fl at.

3. Find a 1 in. long capscrew with correct thread size to
match threads in connecting rod.

4. Use a fl at washer with correct I.D. to slip on
capscrew and approximately 1 in. O.D. Assemble
capscrew and washer to joint surface of rod.

1562 690 05 Rev. -- KohlerEngines.com

Troubleshooting

TROUBLESHOOTING GUIDE

When troubles occur, be sure to check simple causes which, at fi rst, may seem too obvious to be considered. For
example, a starting problem could be caused by an empty fuel tank.

Some general common causes of engine troubles are listed below and vary by engine specifi cation. Use these to
locate causing factors.

Engine Cranks But Will Not Start

● Battery connected backwards.

● Blown fuse.

● Carburetor solenoid malfunction.

● Choke not closing.

● Clogged fuel line or fuel fi lter.

● Diode in wiring harness failed in open circuit mode.

● DSAI or DSAM malfunction.

● Empty fuel tank.

● Faulty electronic control unit.

● Faulty ignition coil(s).

● Faulty spark plug(s).

● Fuel pump malfunction-vacuum hose clogged or

leaking.

● Fuel shut-off valve closed.

● Ignition module(s) faulty or improperly gapped.

● Insuffi cient voltage to electronic control unit.

● Interlock switch is engaged or faulty.

● Key switch or kill switch in OFF position.

● Low oil level.

● Quality of fuel (dirt, water, stale, mixture).

● SMART-SPARKTM malfunction.

● Spark plug lead(s) disconnected.

Engine Starts But Does Not Keep Running

● Faulty carburetor.

● Faulty cylinder head gasket.

● Faulty or misadjusted choke or throttle controls.

● Fuel pump malfunction-vacuum hose clogged or

leaking.

● Intake system leak.

● Loose wires or connections that intermittently ground

ignition kill circuit.

● Quality of fuel (dirt, water, stale, mixture).

● Restricted fuel tank cap vent.

Engine Starts Hard

● Clogged fuel line or fuel fi lter.

● Engine overheated.

● Faulty ACR mechanism.

● Faulty or misadjusted choke or throttle controls.

● Faulty spark plug(s).

● Flywheel key sheared.

● Fuel pump malfunction-vacuum hose clogged or

leaking.

● Interlock switch is engaged or faulty.

● Loose wires or connections that intermittently ground

ignition kill circuit.

● Low compression.

● Quality of fuel (dirt, water, stale, mixture).

● Weak spark.

Engine Will Not Crank

● Battery is discharged.

● Faulty electric starter or solenoid.

● Faulty key switch or ignition switch.

● Interlock switch is engaged or faulty.

● Loose wires or connections that intermittently ground

ignition kill circuit.

● Pawls not engaging in drive cup.

● Seized internal engine components.

Engine Runs But Misses

● Carburetor adjusted incorrectly.

● Engine overheated.

● Faulty spark plug(s).

● Ignition module(s) faulty or improperly gapped.

● Incorrect crankshaft position sensor air gap.

● Interlock switch is engaged or faulty.

● Loose wires or connections that intermittently ground

ignition kill circuit.

● Quality of fuel (dirt, water, stale, mixture).

● Spark plug lead(s) disconnected.

● Spark plug lead boot loose on plug.

● Spark plug lead loose.

Engine Will Not Idle

● Engine overheated.

● Faulty spark plug(s).

● Idle fuel adjusting needle(s) improperly set.

● Idle speed adjusting screw improperly set.

● Inadequate fuel supply.

● Low compression.

● Quality of fuel (dirt, water, stale, mixture).

● Restricted fuel tank cap vent.

Engine Overheats

● Cooling fan broken.

● Excessive engine load.

● Fan belt failed/off.

● Faulty carburetor.

● High crankcase oil level.

● Lean fuel mixture.

● Low cooling system fl uid level.

● Low crankcase oil level.

● Radiator, and/or cooling system components clogged,

restricted, or leaking.

● Water pump belt failed/broken.

● Water pump malfunction.

Engine Knocks

● Excessive engine load.

● Hydraulic lifter malfunction.

● Incorrect oil viscosity/type.

● Internal wear or damage.

● Low crankcase oil level.

● Quality of fuel (dirt, water, stale, mixture).

16 62 690 05 Rev. --KohlerEngines.com

Troubleshooting

Engine Loses Power

● Dirty air cleaner element.

● Engine overheated.

● Excessive engine load.

● Restricted exhaust.

● Faulty spark plug(s).

● High crankcase oil level.

● Incorrect governor setting.

● Low battery.

● Low compression.

● Low crankcase oil level.

● Quality of fuel (dirt, water, stale, mixture).

Engine Uses Excessive Amount of Oil

● Loose or improperly torqued fasteners.

● Blown head gasket/overheated.

● Breather reed broken.

● Clogged, broken, or inoperative crankcase breather.

● Crankcase overfi lled.

● Incorrect oil viscosity/type.

● Worn cylinder bore.

● Worn or broken piston rings.

● Worn valve stems/valve guides.

Oil Leaks from Oil Seals, Gaskets

● Breather reed broken.

● Clogged, broken, or inoperative crankcase breather.

● Loose or improperly torqued fasteners.

● Piston blow by, or leaky valves.

● Restricted exhaust.

EXTERNAL ENGINE INSPECTION

NOTE: It is good practice to drain oil at a location away

from workbench. Be sure to allow ample time for
complete drainage.

Before cleaning or disassembling engine, make a
thorough inspection of its external appearance and
condition. This inspection can give clues to what
might be found inside engines (and cause) when it is
disassembled.

● Check for buildup of dirt and debris on crankcase,

cooling fi ns, grass screen, and other external surfaces.
Dirt or debris on these areas can cause overheating.

● Check for obvious fuel and oil leaks, and damaged

components. Excessive oil leakage can indicate a
clogged or inoperative breather, worn or damaged
seals or gaskets, or loose fasteners.

● Check air cleaner cover and base for damage or

indications of improper fi t and seal.

● Check air cleaner element. Look for holes, tears,

cracked or damaged sealing surfaces, or other
damage that could allow unfi ltered air into engine. A
dirty or clogged element could indicate insuffi cient or
improper maintenance.

● Check carburetor throat for dirt. Dirt in throat is further

indication that air cleaner was not functioning properly.

● Check if oil level is within operating range on dipstick.

If it is above, sniff for gasoline odor.

● Check condition of oil. Drain oil into a container; it

should fl ow freely. Check for metal chips and other
foreign particles.

Sludge is a natural by-product of combustion; a small

accumulation is normal. Excessive sludge formation
could indicate over rich fuel settings, weak ignition,
overextended oil change interval or wrong weight or
type of oil was used.

CLEANING ENGINE

WARNING

Cleaning Solvents can cause severe injury or
death.

Use only in well ventilated areas away from
ignition sources.

Carburetor cleaners and solvents are extremely
fl ammable. Follow cleaner manufacturer’s warnings
and instructions on its proper and safe use. Never use
gasoline as a cleaning agent.

After inspecting external condition of engine, clean
engine thoroughly before disassembly. Clean individual
components as engine is disassembled. Only clean
parts can be accurately inspected and gauged for wear
or damage. There are many commercially available
cleaners that will quickly remove grease, oil, and grime
from engine parts. When such a cleaner is used, follow
manufacturer’s instructions and safety precautions
carefully.

Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.

1762 690 05 Rev. -- KohlerEngines.com

Troubleshooting

CRANKCASE VACUUM TEST

WARNING

Carbon Monoxide can cause severe nausea,
fainting or death.

Avoid inhaling exhaust fumes.

Engine exhaust gases contain poisonous carbon
monoxide. Carbon monoxide is odorless, colorless,
and can cause death if inhaled.

A partial vacuum should be present in crankcase when engine is operating. Pressure in crankcase (normally caused
by a clogged or improperly assembled breather) can cause oil to be forced out at oil seals, gaskets, or other available
spots.

Crankcase vacuum is best measured with either a water manometer or a vacuum gauge. Complete instructions are
provided in kits.

To test crankcase vacuum with manometer:

1. Insert rubber stopper into oil fi ll hole. Be sure pinch
clamp is installed on hose and use tapered adapters
to connect hose between stopper and one
manometer tube. Leave other tube open to
atmosphere. Check that water level in manometer is
at 0 line. Make sure pinch clamp is closed.

2. Start engine and run no-load high speed.

3. Open clamp and note water level in tube.

Level in engine side should be a minimum of 10.2

cm (4 in.) above level in open side.

If level in engine side is less than specifi ed (low/no

vacuum), or level in engine side is lower than level in
open side (pressure), check for conditions in table
below.

4. Close pinch clamp before stopping engine.

Keep hands, feet, hair, and clothing away from all
moving parts to prevent injury. Never operate engine
with covers, shrouds, or guards removed.

To test crankcase vacuum with vacuum/pressure gauge:

1. Remove dipstick or oil fi ll plug/cap.

2. Install adapter into oil fi ll/dipstick tube opening,

3. Run engine and observe gauge reading.
Analog tester–needle movement to left of 0 is a

Digital tester–depress test button on top of tester.
Crankcase vacuum should be a minimum of 10.2 cm

Rotating Parts can cause severe injury.
Stay away while engine is in operation.

upside down over end of a small diameter dipstick
tube, or directly into engine if a tube is not used.
Insert barbed gauge fi tting into hole in stopper.

vacuum, and movement to right indicates a pressure.

(4 in.) of water. If reading is below specifi cation, or if
pressure is present, check table below for possible
causes and conclusions.

WARNING

Condition Conclusion

Crankcase breather clogged or inoperative. NOTE: If breather is integral part of valve cover and

cannot be serviced separately, replace valve
cover and recheck pressure.

Disassemble breather, clean parts thoroughly, check
sealing surfaces for fl atness, reassemble, and recheck
pressure.

Seals and/or gaskets leaking. Loose or improperly torque
fasteners.

Piston blow by or leaky valves (confi rm by inspecting
components).

Restricted exhaust. Check exhaust screen/spark arrestor (if equipped). Clean

Replace all worn or damaged seals and gaskets. Make
sure all fasteners are tightened securely. Use appropriate
torque valves and sequences when necessary.

Recondition piston, rings, cylinder bore, valves and
valves guides.

or replace as needed. Repair or replace any other
damaged/restricted muffl er or exhaust system parts.

18 62 690 05 Rev. --KohlerEngines.com

Troubleshooting

COMPRESSION TEST

For Command Twins:
A compression test is best performed on a warm engine. Clean any dirt or debris away from base of spark plug(s)

before removing them. Be sure choke is off, and throttle is wide open during test. Compression should be at least 160
psi and should not vary more than 15% between cylinders.

All other models:
These engines are equipped with an automatic compression release (ACR) mechanism. It is diffi cult to obtain an

accurate compression reading because of ACR mechanism. As an alternative, use cylinder leakdown test described
below.

CYLINDER LEAKDOWN TEST

A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing combustion chamber
from an external air source you can determine if valves or rings are leaking, and how badly.

Cylinder leakdown tester is a relatively simple, inexpensive leakdown tester for small engines. This tester includes a
quick-connect for attaching adapter hose and a holding tool.

1. Run engine for 3-5 minutes to warm it up.

2. Remove spark plug(s) and air fi lter from engine.

3. Rotate crankshaft until piston (of cylinder being tested) is at top dead center (TDC) of compression stroke. Hold

engine in this position while testing. Holding tool supplied with tester can be used if PTO end of crankshaft is
accessible. Lock holding tool onto crankshaft. Install a 3/8 in. breaker bar into hole/slot of holding tool, so it is
perpendicular to both holding tool and crankshaft PTO.

If fl ywheel end is more accessible, use a breaker bar and socket on fl ywheel nut/screw to hold it in position. An

assistant may be needed to hold breaker bar during testing. If engine is mounted in a piece of equipment, it may
be possible to hold it by clamping or wedging a driven component. Just be certain that engine cannot rotate off of
TDC in either direction.

4. Install adapter into spark plug hole, but do not attach it to tester at this time.

5. Turn regulator knob completely counterclockwise.

6. Connect an air source of at least 50 psi to tester.

7. Turn regulator knob clockwise (increase direction) until gauge needle is in yellow set area at low end of scale.

8. Connect tester quick-connect to adapter hose. While fi rmly holding engine at TDC, gradually open tester valve.

Note gauge reading and listen for escaping air at combustion air intake, exhaust outlet, and crankcase breather.

Condition Conclusion

Air escaping from crankcase breather. Ring or cylinder worn.
Air escaping from exhaust system. Defective exhaust valve/improper seating.
Air escaping from intake. Defective intake valve/improper seating.
Gauge reading in low (green) zone. Piston rings and cylinder in good condition.
Gauge reading in moderate (yellow) zone. Engine is still usable, but there is some wear present.

Customer should start planning for overhaul or
replacement.

Gauge reading in high (red) zone. Rings and/or cylinder have considerable wear. Engine

should be reconditioned or replaced.

1962 690 05 Rev. -- KohlerEngines.com

Air Cleaner/Intake

AIR CLEANER

These systems are CARB/EPA certifi ed and components
should not be altered or modifi ed in any way.

A

D

A Air Cleaner Housing B Inner Element
C Retaining Clip D Element
E End Cap F Dust Ejector Valve

NOTE: Operating engine with loose or damaged air

cleaner components could cause premature
wear and failure. Replace all bent or damaged
components.

NOTE: Paper element cannot be blown out with

compressed air.

1. Unhook retaining clips and remove end cap(s).

2. Check and clean inlet screen (if equipped).

3. Pull air cleaner element out of housing and replace.
Check condition of inner element; replace when dirty.

4. Check all parts for wear, cracks, or damage, and that
ejector area is clean.

5. Install new element(s).

6. Reinstall end cap(s) with dust ejector valve/screen
down; secure with retaining clips.

C

B

E

F

BREATHER TUBE

Ensure both ends of breather tube are properly
connected.

AIR COOLING

WARNING

Hot Parts can cause severe burns.
Do not touch engine while operating or just

after stopping.

Never operate engine with heat shields or guards
removed.

NOTE: Operating engine with a restricted air intake

screen or radiator, damaged/ broken fan
assembly, or missing fan shroud will cause
engine damage due to over heating.

Proper cooling is essential. To prevent over heating,
clean screens, cooling fi ns, and other external surfaces
of engine. Avoid spraying water at wiring harness or any
electrical components. See Maintenance Schedule.

62 690 05 Rev. --KohlerEngines.com20

EFI SYSTEM

WARNING

Explosive Fuel can cause fi res and severe
burns.

Do not fi ll fuel tank while engine is hot or
running.

Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite if it
comes in contact with hot parts or sparks from ignition.
Never use gasoline as a cleaning agent.

Typical electronic fuel injection (EFI) system and related
components include:

● Fuel pump/module and lift pump.

● Fuel fi lter.

● High pressure fuel line.

● Fuel line(s).

● Fuel injectors.

● Throttle body/intake manifold.

● Electronic control unit (ECU).

● Ignition coils.

● Engine (oil) temperature sensor.

● Throttle position sensor (TPS).

● Crankshaft position sensor.

● Oxygen sensor.

● Manifold absolute pressure sensor (MAP).

● Wire harness assembly & affi liated wiring.

● Malfunction indicator light (MIL) - optional.

● Intake air temperature sensor.

FUEL RECOMMENDATIONS

Refer to Maintenance.

FUEL LINE

Low permeation fuel line must be installed on all Kohler
Co. engines to maintain EPA and CARB regulatory
compliance.

OPERATION

NOTE: When performing voltage or continuity tests,

avoid putting excessive pressure on or against
connector pins. Flat pin probes are
recommended for testing to avoid spreading or
bending terminals.

EFI system is designed to provide peak engine
performance with optimum fuel effi ciency and lowest
possible emissions. Ignition and injection functions
are electronically controlled, monitored and continually
corrected during operation to maintain ideal air/fuel ratio.

Central component of system is Engine Control Unit
(ECU) which manages system operation, determining
best combination of fuel mixture and ignition timing for
current operating conditions.

A lift fuel pump is used to move fuel from tank through
an in-line fuel fi lter and fuel line. Fuel is then pumped
to fuel pump module. Fuel pump module regulates
fuel pressure to a system operating pressure of 39 psi.
Fuel is delivered from fuel pump module through high
pressure fuel line into injectors, which inject fuel into
intake ports. ECU controls amount of fuel by varying
length of time that injectors are on. This can range
from 2 to over 12 milliseconds depending on fuel
requirements. Controlled injection of fuel occurs every
other crankshaft revolution, or once for each 4-stroke
cycle. When intake valve opens, air/fuel mixture is drawn
into combustion chamber,compressed, ignited, and
burned.

ECU controls amount of fuel being injected and ignition
timing by monitoring primary sensor signals for engine
temperature, speed (RPM), and throttle position (load).
These primary signals are compared to preprogrammed
maps in ECU computer chip, and ECU adjusts fuel
delivery to match mapped values. After engine reaches
operating temperature, an exhaust gas oxygen sensor
provides feedback to ECU based upon amount of
unused oxygen in exhaust, indicating whether fuel
mixture being delivered is rich or lean. Based upon this
feedback, ECU further adjusts fuel input to re-establish
ideal air/fuel ratio. This operating mode is referred to as
closed loop operation. EFI system operates closed loop
when all three of following conditions are met:

● Oil temperature is greater than 50°C (122°F).

● Oxygen sensor has warmed suffi ciently to provide a

signal (minimum 400°C, 752°F).

● Engine operation is at a steady state (not starting,

warming up, accelerating, etc.).

During closed loop operation ECU has ability to readjust
temporary and learned adaptive controls, providing
compensation for changes in overall engine condition
and operating environment, so it will be able to maintain
ideal air/fuel ratio. This system requires a minimum
engine oil temperature greater than 60°C (140°F) to
properly adapt. These adaptive values are maintained as
long as ECU is not reset.

During certain operating periods such as cold starts,
warm up, acceleration, high load, etc., a richer air/fuel
ratio is required and system operates in an open loop
mode. In open loop operation oxygen sensor output is
used to ensure engine is running rich, and controlling
adjustments are based on primary sensor signals and
programmed maps only. This system operates open
loop whenever three conditions for closed loop operation
(above) are not being met.

ECU is brain or central processing computer of entire
EFI system. During operation, sensors continuously
gather data which is relayed through wiring harness
to input circuits within ECU. Signals to ECU include:
ignition (on/off), crankshaft position and speed (RPM),
throttle position, oil temperature, intake air temperature,
exhaust oxygen levels, manifold absolute pressure, and
battery voltage.

2162 690 05 Rev. -- KohlerEngines.com

EFI SYSTEM

ECU compares input signals to programmed maps in
its memory to determine appropriate fuel and spark
requirements for immediate operating conditions. ECU
then sends output signals to set injector duration and
ignition timing.

ECU continually performs a diagnostic check of itself,
each of sensors, and system performance. If a fault
is detected, ECU can turn on a Malfunction Indicator
Light (MIL) (if equipped) on equipment control panel,
store fault code in its fault memory, and go into a default
operating mode. Depending on signifi cance or severity
of fault, normal operation may continue. A technician can
access stored fault code using a blink code diagnosis
fl ashed out through MIL. An optional computer software
diagnostic program is also available, see Tools and Aids.

ECU requires a minimum of 6.0 volts to operate.
To prevent engine over-speed and possible failure, a

rev-limiting feature is programmed into ECU. If maximum
RPM limit (4500) is exceeded, ECU suppresses injection
signals, cutting off fuel fl ow. This process repeats itself in
rapid succession, limiting operation to preset maximum.

Wiring harness used in EFI system connects electrical
components, providing current and ground paths for
system to operate. All input and output signaling occurs
through two special all weather connectors that attach
and lock to ECU. Connectors are Black and Grey and
keyed differently to prevent being attached to ECU
incorrectly.

Condition of wiring, connectors, and terminal
connections is essential to system function and
performance. Corrosion, moisture, and poor connections
are as likely cause of operating problems and system
errors as an actual component. Refer to Electrical
System for additional information.

EFI system is a 12 VDC negative ground system,
designed to operate down to a minimum of 6.0 volts.
If system voltage drops below this level, operation
of voltage sensitive components such as ECU, fuel
pump, ignition coils, and injectors will be intermittent
or disrupted, causing erratic operation or hard starting.
A fully charged, 12 volt battery with a minimum of 350
cold cranking amps is important in maintaining steady
and reliable system operation. Battery condition and
state of charge should always be checked fi rst when
troubleshooting an operational problem.

Keep in mind that EFI-related problems are often caused
by wiring harness or connections. Even small amounts
of corrosion or oxidation on terminals can interfere with
milliamp currents used in system operation.

Cleaning connectors and grounds will solve problems
in many cases. In an emergency situation, simply
disconnecting and reconnecting connectors may clean
up contacts enough to restore operation, at least
temporarily.

If a fault code indicates a problem with an electrical
component, disconnect ECU connector and test for
continuity between component connector terminals and
corresponding terminals in ECU connector using an
ohmmeter. Little or no resistance should be measured,
indicating that wiring of that particular circuit is OK.

Crankshaft position sensor is essential to engine
operation; constantly monitoring rotation and speed
(RPM) of crankshaft. There are 23 consecutive teeth
cast into fl ywheel. One tooth is missing and is used
to reference crankshaft position for ECU. Inductive
crankshaft position sensor is mounted 0.20-0.70 mm
(0.008-0.027 in.) from fl ywheel.

During rotation, an AC voltage pulse is created within
sensor for each passing tooth. ECU calculates engine
speed from time interval between consecutive pulses.
Gap from missing tooth creates an interrupted input
signal, corresponding to specifi c crankshaft position near
BDC for cylinder #1. This signal serves as a reference
for control of ignition timing by ECU. Synchronization of
inductive speed pickup and crankshaft position takes
place during fi rst two revolutions each time engine is
started. Sensor must be properly connected at all times.
If sensor becomes disconnected for any reason, engine
will quit running.

Throttle position sensor (TPS) is used to indicate throttle
plate angle to ECU. Since throttle (by way of governor)
reacts to engine load, angle of throttle plate is directly
related to load on engine.

Mounted on throttle body and operated directly off end
of throttle shaft, TPS works as a potentiometer, varying
voltage signal to ECU in direct correlation to angle
of throttle plate. This signal, along with other sensor
signals, is processed by ECU and compared to internal
preprogrammed maps to determine required fuel and
ignition settings for amount of load.

Correct position of TPS is established and set at factory.
Do not loosen TPS or alter mounting position unless
absolutely required by fault code diagnosis. If TPS
is loosened or repositioned, appropriate TPS Learn
Procedure must be performed to re-establish baseline
relationship between ECU and TPS.

Engine (oil) temperature sensor is used by system to
help determine fuel requirements for starting (a cold
engine needs more fuel than one at or near operating
temperature).

Mounted in crankcase next to breather cover, it has
a temperature-sensitive resistor that extends into oil
fl ow. Resistance changes with oil temperature, altering
voltage sent to ECU. Using a table stored in its memory,
ECU correlates voltage drop to a specifi c temperature.
Using fuel delivery maps, ECU then knows how much
fuel is required for starting at that temperature.

Intake Air Temperature (IAT) sensor is a thermally
sensitive resistor that exhibits a change in electrical
resistance with a change in its temperature.

When sensor is cold, resistance of sensor is high. As
sensor warms up, resistance drops and voltage signal
increases. From voltage signal, ECU can determine
temperature of intake air.

Purpose of an air temperature sensor is to help ECU
calculate air density. Higher air temperature less dense
air becomes. As air becomes less dense ECU knows
that it needs to lessen fuel fl ow to achieve correct air/fuel
ratio. If fuel ratio was not changed engine would become
rich, possibly losing power and consuming more fuel.

Oxygen sensor functions like a small battery, generating
a voltage signal to ECU based upon difference in oxygen
content between exhaust gas and ambient air.

22

62 690 05 Rev. --KohlerEngines.com

EFI SYSTEM

Tip of sensor, protruding into exhaust gas, is hollow.
Outer portion of tip is surrounded by exhaust gas, with
inner portion exposed to ambient air. When oxygen
concentration on one side of tip is different than that of
other side, a voltage signal up to 1.0 volt is generated
and sent to ECU. Voltage signal tells ECU if engine is
straying from ideal fuel mixture, and ECU then adjusts
injector pulse accordingly.

Oxygen sensor functions after being heated to a
minimum of 400°C (752°F). A heater inside sensor heats
electrode to optimum temperature in about 10 seconds.
Oxygen sensor receives ground through wire, eliminating
need for proper grounding through muffl er. If problems
indicate a bad oxygen sensor, check all connections and
wire harness. Oxygen sensor can also be contaminated
by leaded fuel, certain RTV and/or other silicone
compounds, fuel injector cleaners, etc. Use only those
products indicated as O2 Sensor Safe.

Manifold absolute pressure (MAP) sensor provides
immediate manifold pressure information to ECU.
MAP measures difference in pressure between outside
atmosphere and vacuum level inside intake manifold
and monitors pressure in manifold as primary means
of detecting load. Data is used to calculate air density
and determine engine's mass air fl ow rate, which in
turn determines required ideal fueling. MAP also stores
instant barometric pressure reading when key is turned
ON.

Fuel injectors mount into intake manifold, and high
pressure fuel line attaches to them at top end.
Replaceable O-rings on both ends of injector prevent
external fuel leakage and also insulate it from heat and
vibration. A special clip connects each injector to high
pressure fuel line and holds it in place. O-rings and
retaining clip must be replaced any time fuel injector is
separated from its normal mounting position.

When key switch is on, fuel pump module will pressurize
high pressure fuel line to 39 psi, and voltage is present
at injector. At proper instant, ECU completes ground
circuit, energizing injector. Valve needle in injector
is opened electromagnetically, and pressure in high
pressure fuel line forces fuel down through inside.
Director plate at tip of injector contains a series of
calibrated openings which directs fuel into manifold in a
cone-shaped spray pattern.

Injectors have sequential fueling that open and close
once every other crankshaft revolution. Amount of fuel
injected is controlled by ECU and determined by length
of time valve needle is held open, also referred to as
injection duration or pulse width. Time injector is open
(milliseconds) may vary in duration depending on speed
and load requirements of engine.

A high-voltage, solid-state, battery ignition system is
used with EFI system. ECU controls ignition output and
timing through transistorized control of primary current
delivered to coils. Based on input from crankshaft
position sensor, ECU determines correct fi ring point
for speed at which engine is running. At proper instant,
it interrupts fl ow of primary current in coil, causing
electromagnetic fl ux fi eld to collapse. Flux collapse
induces an instantaneous high voltage in coil secondary
which is strong enough to bridge gap on spark plug.
Each coil fi res every other revolution.

EFI engines are equipped with either a 20 or 25 amp
charging system to accommodate combined electrical
demands of ignition system and specifi c application.
Charging system troubleshooting information is provided
in Electrical System.

An electric fuel pump module and a lift pump (two types)
are used to transfer fuel in EFI system. Two types of
lift pumps are: a pulse fuel pump or a low pressure
electric fuel pump. Pumping action is created by either
oscillation of positive and negative pressures within
crankcase through a hose, or by direct lever/pump
actuation off rocker arm movement. Pumping action
causes diaphragm on inside of pump to pull fuel in on its
downward stroke and to push it into fuel pump module
on its upward stroke. Internal check valves prevent fuel
from going backward through pump. Fuel pump module
receives fuel from lift pump, increases and regulates
pressure for fuel injectors.

Fuel pump module is rated for a minimum output of 13.5
liters per hour and regulated at 270 kilo pascals (39 psi).

When key switch is turned ON and all safety switch
requirements are met, ECU activates fuel pump module
for about six seconds, which pressurizes system for
start-up. If key switch is not promptly turned to start
position, engine fails to start, or engine is stopped with
key switch ON (as in case of an accident), ECU switches
off pump preventing continued delivery of fuel. In this
situation, MIL will go on, but it will go back off after 4
cranking revolutions if system function is OK. Once
engine is running, fuel pump remains on.

Precision components inside fuel pump module are not
serviceable. DO NOT attempt to open fuel pump module.
Damage to components will result and warranty will be
void. Because fuel pump module is not serviceable,
engines are equipped with a special 10-micron EFI fuel
fi lter to prevent harmful contamination from entering
module.

If there are two fi lters in system, one before lift pump
will be a standard 51-75 micron fi lter, and one after lift
pump will be special 10-micron fi lter. Be sure to use an
approved 10-micron fi lter for replacement.

High pressure fuel line is an assembly of hoses, injector
caps and a fuel connector to fuel pump module. High
pressure fuel line feeds fuel to top of injectors through
injector caps. Caps are fastened to intake manifold and
injectors are locked into place. A small retaining clip
provides a secondary lock.

2362 690 05 Rev. -- KohlerEngines.com

EFI SYSTEM

High pressure fuel line is serviced as a complete
assembly to prevent tampering and safety hazards.
Components are not individually serviceable.

Vent hose assembly is intended to vent fuel vapor out of
fuel pump module and direct fuel vapor into throttle body.
All EFI engines are equipped with an engine mounted
purge port on #2 cylinder barrel baffl e. This capped
purge port can be used by OEM to vent fuel tanks or
used in conjunction with a carbon canister kit for Tier III
evaporative emissions compliance. Purge port connects
to vent hose assembly and directs all fuel vapor into
throttle body. If purge port remains unused, port must
remain capped to prevent dirt from entering engine.

EFI engines have no carburetor, so throttle function
(regulate incoming combustion airfl ow) is achieved with
a throttle valve in a separate throttle body attached to
intake manifold. Throttle body/intake manifold provides
mounting for fuel injectors, throttle position sensor, MAP
sensor, intake air temperature sensor, high pressure fuel
line, idle speed screw, and air cleaner assembly.

Idle speed is only adjustment that may be performed on
EFI system. Standard idle speed setting for EFI engines
is 1500 RPM, but certain applications might require
a different setting. Check equipment manufacturer’s
recommendation.

For starting and warm up, ECU will adjust fuel and
ignition timing, based upon ambient temperature, engine
temperature, and loads present. In cold conditions,
idle speed will probably be different than normal for a
few moments. Under other conditions, idle speed may
actually start lower than normal, but gradually increase
to established setting as operation continues. Do not
attempt to circumvent this warm up period, or readjust
idle speed during this time. Engine must be completely
warmed up, in closed loop operating mode for accurate
idle adjustment.

IMPORTANT NOTES!

● Cleanliness is essential and must be maintained at all

times when servicing or working on EFI system. Dirt,
even in small quantities, can cause signifi cant
problems.

● Clean any joint or fi tting with parts cleaning solvent

before opening to prevent dirt from entering system.

● Always depressurize fuel system through fuel

connector on fuel pump module before disconnecting
or servicing any fuel system components.

● Never attempt to service any fuel system component

while engine is running or ignition switch is ON.

● Do not use compressed air if system is open. Cover

any parts removed and wrap any open joints with
plastic if they will remain open for any length of time.
New parts should be removed from their protective
packaging just prior to installation.

● Avoid direct water or spray contact with system

components.

● Do not disconnect or reconnect ECU wiring harness

connector or any individual components with ignition
on. This can send a damaging voltage spike through
ECU.

● Do not allow battery cables to touch opposing

terminals. When connecting battery cables attach
positive (+) cable to positive (+) battery terminal fi rst,
followed by negative (-) cable to negative (-) battery
terminal.

● Never start engine when cables are loose or poorly

connected to battery terminals.

● Never disconnect battery while engine is running.

● Never use a quick battery charger to start engine.

● Do not charge battery with key switch ON.

● Always disconnect negative (-) battery cable before

charging battery, and also unplug harness from ECU
before performing any welding on equipment.

24

62 690 05 Rev. --KohlerEngines.com

EFI SYSTEM

ELECTRICAL COMPONENTS
Electronic Control Unit (ECU)
Pinout of ECU

Black Connector

Pin # Function

1 Ignition Coil #1 Ground
2 Battery Ground
3 Diagnostic Communication Line
4 Speed Sensor input
5 Fuel Injector Output #1 Ground
6 Fuel Injector Output #2 Ground
7 Oxygen Sensor Heater
8 Intake Air Temperature (IAT) sensor input

9 Fuel Pump Ground
10 Ground for IAT, TPS, MAP, O2 and Oil Sensors
11 Manifold Absolute Pressure (MAP) sensor input
12 Throttle Position Sensor (TPS) input
13 Speed Sensor Ground
14 Oil Temperature Sensor input
15 Ignition Switch (Switched +12V)
16 Power for TPS and MAP Sensors (+5V)
17 Oxygen Sensor (O2) input
18 Battery Power (Permanent +12V)

Grey Connector

Pin # Description

1 Not Used
2 Not Used
3 Malfunction Indicator Light (MIL) Ground
4 Not Used
5 Not Used
6 GCU Tach Output
7 Not Used
8 Not Used

9 Battery Ground
10 Ignition Coil #2 Ground
11 Not Used
12 Not Used
13 Not Used
14 Safety Switch Ground
15 Not Used
16 ECU
17 Fuel Pump Control (+12V)
18 Not Used

Pinout of ECU

2562 690 05 Rev. -- KohlerEngines.com

EFI SYSTEM

Never attempt to disassemble ECU. It is sealed to
prevent damage to internal components. Warranty is
void if case is opened or tampered with in any way.

All operating and control functions within ECU are
preset. No internal servicing or readjustment may
be performed. If a problem is encountered, and you
determine ECU to be faulty, contact your source of
supply.

ECU pins are coated at factory with a thin layer of
electrical grease to prevent fretting and corrosion. Do not
attempt to remove grease from ECU pins.

Relationship between ECU and throttle position sensor
(TPS) is very critical to proper system operation. If
TPS or ECU is changed, or mounting position of TPS
is altered, appropriate TPS Learn Procedure must be
performed to restore synchronization.

Any service to ECU, TPS/Throttle Body (including idle
speed increase over 300 RPM), or fuel pump module
replacement should include ECU Reset.

This will clear all trouble codes, all closed loop learned
offsets, all max values, and all timers besides permanent
hour meter.

This system will NOT reset when battery is
disconnected!

ECU Reset Procedure

1. Turn key/ignition OFF.

2. Install Red wire jumper from Kohler EFI service kit
on to service port (connect white wire to black wire in
4 way diagnostic port).

3. Turn key/ignition ON, then OFF and count 10
seconds.

4. Turn key/ignition ON, then OFF and count to 10
seconds a second time.

5. Remove Red wire jumper. Turn key/ignition ON, then
OFF and count to 10 seconds a third time. ECU is
reset.

A TPS Learn Procedure must be performed after ECU
Reset.

TPS Learn Procedure

1. Turn idle screw clockwise one full turn prior to key/
ignition ON after ECU Reset.

2. Start engine, run at low idle until engine is warm.

3. Idle speed must be above 1500 RPM. If below 1500
RPM, turn idle screw up to 1700 RPM and then shut
down engine and perform ECU Reset again.

4. Adjust idle speed down to 1500 RPM. Allow engine
to dwell at 1500 RPM for about 3 seconds.

5. After this, adjust idle speed to fi nal specifi ed speed
setting.

6. Turn key/ignition OFF and count to 10 seconds.

Learn procedure is complete.

26

62 690 05 Rev. --KohlerEngines.com

EFI SYSTEM

Sensor

U

B

Intake Air

M G

T

G

S

AM

F

R

M

Q

V

A

M

K

C

I

B

AP

A

W

J

W

K

J

M

M

F

E

M

G L

L

M

M

H

F

D B

H

AJ

AI

AH

AG

AF

AE

AD

O Rectifi er-Regulator

Stator

Crankshaft Position

Temperature Sensor

AI

Sensor

Oil Temperature

EFI Oil Temperature

Manifold Absolute

Sensor (some models)

AH

AM

only

Pressure Sensor

Electronic Governor

AG

O

Wiring Diagram

AL

H

H

M

N

Y

AK

M B

B

B

F

B

G

X

AC

AB

AA

Z

A Red B Red/Black C Red/White D Yellow E Light Green

F Dark Green G Dark Blue H Purple I Pink J Ta n

K White L Grey M Black N

Throttle Position

P 30A Fuse Q Battery R Fuel Pump S 6-Terminal Connector T Starter Motor

Z Fuel Injector #1 AA Fuel Injector #2 AB Ignition Coil #1 AC Ignition Coil #2 AD

U Oil Pressure Switch V MIL W 10A Fuse X Black Connector Y Grey Connector

Sensor

AE Oxygen Sensor AF

AJ Diagnostic Connector AK Grey/Blue AL

2762 690 05 Rev. -- KohlerEngines.com

EFI SYSTEM

Crankshaft Position Sensor

A sealed, non-serviceable assembly. If Fault Code
diagnosis indicates a problem within this area, test and
correct as follows.

1. Remove #2 side cylinder shroud to access. Check
mounting and air gap of sensor. It must be 0.20-0.70
mm (0.008-0.027 in.).

2. Inspect wiring and connections for damage or
problems.

3. Make sure engine has resistor type spark plugs.

4. Disconnect Black connector from ECU.

5. Connect an ohmmeter between #4 and #13 pin
terminals. A resistance value of 325-395 Ω at room
temperature (20°C, 68°F) should be obtained. If
resistance is correct, check mounting, air gap,
fl ywheel teeth (damage, run-out, etc.), and fl ywheel
key.

6. Disconnect crankshaft position sensor connector
from wiring harness. Test resistance between
terminals. A reading of 325-395 Ω should again be

obtained.

a. If resistance is incorrect, remove screws securing

sensor to mounting bracket and replace sensor.

b. If resistance in step 5 was incorrect, but

resistance of sensor alone was correct, test wire
harness circuits between sensor connector
terminals and corresponding pin terminals (#4
and #13) in main connector. Correct any
observed problem, reconnect sensor, and
perform step 5 again.

7. When fault is corrected and engine starts, clear fault
codes following ECU Reset procedure.

Throttle Position Sensor (TPS)
Resistance Table

Throttle

Position

Closed A & C 1400-1800 Yes

Full with

Stop Pin

Full without

Stop Pin

Any A & B 3000-7000 Yes

TPS is a sealed, non-serviceable assembly. If diagnosis
indicates a bad sensor, complete replacement is
necessary. If a blink code indicates a problem with TPS,
it can be tested as follows:

1. Counting number of turns, back out idle speed
adjusting screw (counterclockwise) until throttle
plates can be closed completely. Write this number
down for reference later.

2. Disconnect Black connector from ECU, but leave
TPS mounted to throttle body.

3. a. Use an ohmmeter and connect red (positive)

ohmmeter lead to Black pin 12 terminal and black
(negative) ohmmeter lead to Black pin 10 terminal
to test.

Between
Terminal

A & C 3200-4100 Yes

A & C 4600-5200 Yes

Resistance

Value (Ω)

Continuity

b. Hold throttle closed and check resistance. It

should be 1400-1800 Ω.

4. Leave leads connected to pin terminals as described
in step 3. Rotate throttle shaft slowly to full throttle
position. Monitor dial during rotation for indication of
any momentary short or open circuits. Note
resistance at full throttle position. It should be
4600-5200 Ω without a stop pin, or 3200-4100 Ω
with a stop pin.

5. Disconnect main wiring harness connector from
TPS, leaving TPS assembled to throttle body. Refer
to Resistance Table and perform resistance checks
indicated between terminals in TPS switch, with
throttle in positions specifi ed.

If resistance values in steps 3, 4, and 5 are within

specifi cations, go to step 6.

If resistance values are not within specifi cations, or a

momentary short or open circuit was detected during
rotation (step 4), TPS needs to be replaced, go to
step 7.

6. Check TPS circuits (input, ground) between TPS
plug and main harness connector for continuity,
damage, etc. Input pin is 12 and ground is pin 10.

a. Repair or replace as required.
b. Turn idle speed screw back in to its original

setting.

c. Reconnect connector plugs, start engine and

retest system operation.

7. #1 side fuel injector electrical connector may be
removed to access fastening screws. Remove two
mounting screws from TPS. Save screws for reuse.
Remove and discard faulty TPS. Install replacement
TPS and secure with original mounting screws.

a. Reconnect Black and TPS connector plugs.

Reconnect electrical connector to #1 side fuel
injector.

b. Perform TPS Learn Procedure integrating new

sensor to ECU.

Engine (Oil) Temperature Sensor

A sealed, non-serviceable assembly. A faulty sensor
must be replaced. If a blink code indicates a problem
with temperature sensor, it can be tested as follows:

1. Remove temperature sensor from crankcase and
cap or block sensor hole.

2. Wipe sensor clean and allow it to reach room
temperature (25°C, 77°F).

3. Unplug Black connector from ECU.

4. With sensor still connected, check temperature
sensor circuit resistance between Black pin 10 and
14 terminals. Value should be 9000-11000 Ω.

5. Unplug sensor from wire harness and check sensor
resistance separately across two pins. Resistance
value should again be 9000-11000 Ω.

a. If resistance is out of specifi cations, replace

temperature sensor.

b. If it is within specifi cations, proceed to Step 6.

28

62 690 05 Rev. --KohlerEngines.com

EFI SYSTEM

6. Check circuits (input, ground), from wire harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 14 in wire
harness connector (as in step 4). Connect other lead
to terminal #1 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #2 in sensor plug.

Intake Air Temperature Sensor

A non-serviceable component. Complete replacement is
required if it is faulty. Sensor and wiring harness can be
checked as follows. Carefully unseat both clips securing
main fuel line to air cleaner bracket to access sensor.

1. Remove temperature sensor from throttle body.

2. Allow it to reach room temperature (20°C, 68°F).

3. Unplug Black connector from ECU.

4. With sensor still connected, check temperature
sensor circuit resistance between Black pin 10 and 8
pin terminals. Value should be 3100-3900 Ω.

5. Unplug sensor from wire harness and check sensor
resistance separately across two pins. Resistance
value should again be 3100-3900 Ω.

a. If resistance is out of specifi cations, replace

temperature sensor.

b. If it is within specifi cations, proceed to Step 6.

6. Check circuits (input, ground), from main harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 8 in main
harness connector (as in step 4). Connect other lead
to terminal #1 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #2 in sensor plug.

7. Reinstall sensor and reposition main fuel line back
into clips on air cleaner bracket.

Oxygen Sensor (O2)

Components

Pin A

Pin D

Cutaway Oxygen Sensor Components (O2)

Pin B

Pin C

D

E

A

B

A Protection Shield B

C Lower Insulator D

E Upper Insulator F

G

Temperature must be controlled very accurately and gas
constituents measured to a high degree of accuracy for
absolute sensor measurements. This requires laboratory
equipment to determine a good or bad sensor in fi eld.
Furthermore, as with most devices, intermittent problems
are diffi cult to diagnose. Still, with a good understanding
of system and sensor, it is possible to diagnose many
sensor problems in fi eld.

Using diagnostic software connected to ECU is a useful
technique for observing sensor performance. However,
user must understand that such software reads a signal
generated by ECU. If there is an ECU or wiring problem,
readings could be misinterpreted as a sensor problem.
Digital nature of signal to software means that it is not
reading continuous output of sensor. A voltmeter can
also be used as an effective tool in diagnosing sensors.
It is advisable to use an electronic meter such as a
digital voltmeter. Simple mechanical meters may place
a heavy electrical load on sensor and cause inaccurate
readings. Since resistance of sensor is highest at
low temperatures, such meters will cause largest
inaccuracies when sensor is in a cool exhaust.

Visual Inspection

1. Look for a damaged or disconnected sensor-to­engine harness connection.

2. Look for damage to sensor lead wire or associated
engine wiring due to cutting, chaffi ng or melting on a
hot surface.

3. Disconnect sensor connector and look for corrosion
in connector.

4. Try reconnecting sensor and observe if problem has
cleared.

5. Correct any problems found during visual check.

High Temp

Water Seal

C

F

Planar Element

and Heater

Stainless Steel

Housing

Terminal Connection

to Element

G

2962 690 05 Rev. -- KohlerEngines.com

EFI SYSTEM

Sensor Signal Observation
NOTE: Do not cut into or pierce sensor or engine

wiring to make this connection. Sensor

produces a very small signal. Corrosion or
damage to wiring could lead to an incorrect
signal because of repairs or contamination to
sensor.

1. Using a voltmeter or diagnostic software observe
voltage before engine is started. With key ON,
voltage should read about 1.0 volt. This voltage is
generated by ECU. If it is not present, disconnect
sensor and observe voltage at harness connector. If
voltage is now present, there is a short in sensor or
associated wiring and corrective action should be
taken. If voltage still is not present, there is a
problem with ECU or engine harness.

2. Reconnect sensor and start engine. Run engine at
suffi cient speed to bring sensor up to operating
temperature. Maintain for 1 to 2 minutes to ensure
that engine has gone closed loop. Once in closed
loop, sensor voltage should cycle between about
100 to 250 mv (low speed idle) and 700 to 900 mv
(high speed no load). If this cycling is not observed,
a determination must be made, if problem is with
engine or sensor.

3. Check engine harness for battery voltage on heater
circuit.

Removal Inspection

NOTE: Apply anti-seize compound only to threads.

Anti-seize compound will affect sensor
performance if it gets into lower shield of
sensor.

1. If sensor has heavy deposits on lower shield,
engine, oil, or fuel may be source.

2. If heavy carbon deposits are observed, incorrect
engine fuel control may be occurring.

3. If sensor is at room temperature, measure between
signal leads, black wire (Pin C) and grey wire (Pin D)
attached to sensor. If resistance is less than one
megohm, sensor has an internal short.

4. With sensor at room temperature measure heater
circuit resistance, purple wire (Pin A) and white wire
(Pin B), resistance should be 8.1-11.1 Ω.

5. If a damaged sensor is found, identify root cause,
which may be elsewhere in application. Refer to
Troubleshooting-Oxygen Sensor (O2) table.

6. A special "dry to touch" anti-seize compound is
applied to all new oxygen sensors at factory. If
recommended mounting thread sizes are used, this
material provides excellent anti-seize capabilities
and no additional anti-seize is needed. If sensor is
removed from engine and reinstalled, anti-seize
compound should be reapplied. Use an oxygen
sensor safe type anti-seize compound. It should be
applied according to directions on label.

30

62 690 05 Rev. --KohlerEngines.com