Graco 308870 User Manual
INSTRUCTIONS-REPAIR
308870
KEEP FOR REFERENCE.
Read this and all related manuals for
important warnings and instructions.
INSTRUCTIONS
GMaxr 7900
Airless Paint Sprayer
3300 psi (227 bar, 22.7 MPa ) Maximum Working Pressure
GMax 7900
Model Series Description
232630 A Hi-Boy
232631 A Hi-Boy with RAC IV tip, gun and hose
232632 A Lo-Boy
232633 A Lo-Boy with RAC IV tip, gun and hose
All models are not available in all countries
PATENTS PENDING
First choice when
quality counts.
t
Rev. B
Related Manuals
Operation 308867. . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump 308798. . . . . . . . . . . . . . . . .
Spray Gun 307614. . . . . . . . . . . . . . . . . . . . . . . . .
Spray Tip 308644. . . . . . . . . . . . . . . . . . . . . . . . . . .
PC Board 308919. . . . . . . . . . . . . . . . . . . . . . . . . .
Drain Valve Kit 308961. . . . . . . . . . . . . . . . . . . . . .
Table of Contents
Warnings and Cautions 2. . . . . . . . . . . . . . . . . . . . . . . . .
Component Identification and Function 3. . . . . . . . . . . .
Maintenance 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair
Rollers 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive Housing 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cam Follower Bearings 8. . . . . . . . . . . . . . . . . . . . . . .
Pinion Assembly/Rotor/Field/Shaft/Clutch 9. . . . . . . .
Clamp 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch Housing 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9035A
Pressure Control 13. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump 15. . . . . . . . . . . . . . . . . . . . . . . . .
Parts
Pinion Assembly 17. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hi-Boy Sprayers 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lo-Boy Sprayers 20. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Control 22. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Complete Sprayers 24. . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Phone Number 25. . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Warranty 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
ECOPYRIGHT 1999, GRACO INC.
Graco Inc. is registered to I.S. EN ISO 9001
Warnings and Cautions
Warning Symbol
WARNING
This symbol alerts you to the possibility of serious
injury or death if you do not follow the instructions.
WARNING
Fire and explosion can occur when spraying or flushing flammable
fluid in an area where air circulation is poor and flammable vapors
can be ignited by an open flame or sparks.
To help prevent a fire and explosion:
Use outdoors or in an extremely well ventilated area.
Do not use 1,1,1–trichloroethane, methylene chloride, other
halogenated hydrocarbon solvents or fluids containing such
solvents in pressurized aluminum equipment. Such use could
result in a chemical reaction, with the possibility of explosion.
Remove, extinguish or unplug all ignition sources;
tape wall switch. Do not smoke in spray area.
Never fill fuel tank while the engine is running or hot.
Ground Sprayer, object being sprayed, paint and solvent pails.
Hold gun firmly to side of a grounded pail when triggering into pail.
Use only conductive airless paint hose.
Never run engine in inclosed area.
Caution Symbol
CAUTION
This symbol alerts you to the possibility of damage to
or destruction of equipment if you do not follow the
instructions.
Fluid injection is a serious injury! If high pressure fluid pierces
your skin, the injury might look like “just a cut”. But it is a serious
wound! Get immediate medical attention.
To help prevent injection, always:
Engage trigger safety latch when not spraying.
Point gun away from yourself or anyone else.
Relieve pressure before checking or repairing any leak.
Relieve pressure when you turn off the sprayer or stop spraying.
Do not use components rated less than system
Working Pressure
Never allow children to use this unit. If you are injured using this
equipment, get immediate medical treatment.
Maximum
3088702
Component Identification and Function
202 Main hose
203 Whip end hose
204 Contractor gun with RAC IV
DripLess tip guard and 517 size SwitchTip
K
A
M
X
Fig. 1
V
P
B
U
L
N
C
D
J
H
E
R
S
W
T
203
G
F
Model 232631
202
204
9034A
A Pressure Control Switch ON/OFF, enables/disables clutch function and pressure control
B Pressure Adjusting Knob Controls fluid outlet pressure
C Air Cleaner* Filters air entering the carburetor
D Fuel Tank* Uses 86 octane unleaded gasoline
E Muffler* Reduces noise of internal combustion
F Spark Plug Cable* Routes electrical current to spark plug
G Fuel Shutoff Lever* On/off lever to regulate fuel flow from gasoline tank to carburetor
H Choke* Enriches air/gasoline mixture for cold starting
J Throttle Lever* Adjusts engine speed for large or small orifice spray tips
K Engine Switch* Enables/disables engine operation
L Secondary Fluid Outlet Second hose and spray gun is connected here
M Pressure Control Controls clutch cycling to maintain fluid pressure.
N Primary Fluid Outlet Hose and spray gun is connected here
P Engine* 4–cycle gasoline engine
R Clutch Housing Transfers power from engine to drive assembly
S Drive Housing Transfers power from clutch to displacement pump
T Displacement Pump Provides fluid to be sprayed through spray gun
U Fluid Filter Filters fluid between source and spray gun
V Grounding Clamp and Wire Grounds sprayer system
W Pail Hanger Provides a hanger for paint pail
X Drain Valve Relieves fluid pressure when open
* For more detailed explanations of these controls, refer to the Honda Engines Owner ’s Manual; supplied
Maintenance
WARNING
INJECTION HAZARD
The system pressure must be manually
relieved to prevent the system from
starting or spraying accidentally. Fluid
under high pressure can be injected through the
skin and cause serious injury. To reduce the risk of
an injury from injection, splashing fluid, or moving
parts, follow the Pressure Relief Procedure
whenever you:
are instructed to relieve the pressure,
stop spraying,
check or service any of the system equipment,
or install or clean the spray tip.
Pressure Relief Procedure
1. Lock gun trigger safety.
2. Turn engine ON/OFF switch to OFF.
3. Move pressure control switch to OFF and turn
pressure control knob fully counterclockwise.
CAUTION
For detailed engine maintenance and specifications,
refer to separate Honda Engines Owner’s Manual,
supplied.
DAILY: Check engine oil level and fill as necessary.
DAILY: Check hose for wear and damage.
DAILY: Check gun safety for proper operation.
DAILY: Check pressure drain valve for proper opera-
tion.
DAILY: Check and fill the gas tank.
AFTER THE FIRST 20 HOURS OF OPERATION:
Drain engine oil and refill with clean oil. Reference
Honda Engines Owner’s Manual for correct oil viscosity.
WEEKLY: Remove air filter cover and clean element.
Replace element, if necessary. If operating in an
unusually dusty environment: check filter daily and
replace, if necessary.
4. Unlock trigger safety. Hold metal part of gun firmly
to side of grounded metal pail, and trigger gun to
relieve pressure.
5. Lock gun trigger safety.
6. Open pressure drain valve. Leave valve open until
ready to spray again.
If you suspect that the spray tip or hose is completely
clogged, or that pressure has not been fully relieved
after following the steps above,
loosen tip guard retaining nut or hose end coupling to
relieve pressure gradually, then loosen completely.
Now clear tip or hose.
VERY SLOWLY
Replacement elements can be purchased from your
local HONDA dealer.
WEEKLY: Check level of TSL in displacement pump
packing nut. Fill nut, if necessary. Keep TSL in nut to
help prevent fluid buildup on piston rod and premature
wear of packings.
AFTER EACH 100 HOURS OF OPERATION:
Change engine oil. Reference Honda Engines Owner’s
Manual for correct oil viscosity.
SPARK PLUG: Use only BPR6ES (NGK) or
W20EPR–U (NIPPONDENSO) plug. Gap plug to
0.028 to 0.031 in. (0.7 to 0.8 mm). Use spark plug
wrench when installing and removing plug.
3088704
Troubleshooting
WARNING
INJECTION HAZARD
To reduce risk of serious injury, including fluid injection or splashing in eyes or on skin, or injury from
moving parts, always follow Pressure Relief Procedure Warning, page 4, before checking, adjust-
ing, cleaning or shutting down sprayer.
PROBLEM CAUSE SOLUTION
Engine won’t start
Engine operates, but disp
placement pump does not
operate
p
p
Engine switch is OFF Turn engine switch ON
Engine is out of gas Refill gas tank. Honda Engines Owner’s Manu-
Engine oil level is low Try to start engine. Replenish oil, if necessary.
Spark plug cable is disconnected or damaged Connect spark plug cable or replace spark
Cold engine Use choke
Fuel shutoff lever is OFF Move lever to ON position
Oil is seeping into combustion chamber Remove spark plug. Pull starter rope 3 or 4
Pressure control switch is OFF Turn pressure control switch ON.
Pressure setting is too low Turn pressure adjusting knob clockwise to
Fluid filter (318) is dirty Clean filter. Page 22.
Tip or tip filter is clogged Clean tip or tip filter. Manual 307614.
Displacement pump piston rod is stuck due to
dried paint
al.
Honda Engines Owner’s Manual.
plug
times. Clean or replace spark plug. Try to start
engine. Keep sprayer upright to avoid oil seepage.
increase pressure.
Repair pump. Manual 308798.
Roller bearings are worn or damaged Replace connecting rod. Page 7.
Drive housing is worn or damaged Replace drive housing. Page 7.
Electrical power is not energizing clutch field Check wiring connections. Page 11.
Reference control board diagnostics. Page 14.
With pressure control switch ON and pressure
turned to MAXIMUM, use a test light to check
for power between clutch terminals on control
board.
Remove black clutch wires from control board
and measure resistance across wires. At 70
F, the resistance must be between 1.7
not, replace clutch coil 241121.
Check control board fuse. If blown, replace
with equivalent automotive fuse.
Have pressure control checked by authorized
Graco dealer.
Clutch is worn or damaged Replace clutch. Page 9.
Pinion assembly is worn or damaged Repair or replace pinion assembly. Page 9.
±0.2Ω; if
308870 5
PROBLEM CAUSE SOLUTION
Pump output is low
Excessive paint leakage into
throat packing nut
Strainer (31) is clogged Clean strainer
Piston ball (25) is not seating Service piston ball. Manual 308798.
Piston packings are worn or damaged Replace packings. Manual 308798.
O-ring (227) in displacement pump is worn or
damaged
Intake valve ball is not seating properly Clean intake valve. manual 308798.
Engine speed is too low Increase throttle setting. Manual 308867.
Clutch is worn or damaged Replace clutch. Page 9.
Pressure setting is too low Increase pressure. Manual 308867.
Fluid filter (318), tip filter or tip is clogged or
dirty
Large pressure drop in hose with heavy
materials
Throat packing nut is loose Remove throat packing nut spacer. Tighten
Throat packings are worn or damaged Replace packings. Manual 308798.
Replace o-ring. Manual 308798.
Clean filter. Manual 308867 or 307614.
Use larger diameter hose and/or reduce overall
length of hose. Use of more than 100 ft of 1/4
in. hose significantly reduces performance of
sprayer. Use 3/8 in. hose for optimum performance (50 ft minimum).
throat packing nut just enough to stop leakage.
Fluid is spitting from gun
Pump is difficult to prime
Clutch squeaks each time
clutch engages
Displacement rod is worn or damaged Replace rod. Manual 308798.
Air in pump or hose Check and tighten all fluid connections.
Tip is partially clogged Clear tip. Manual 307614.
Fluid supply is low or empty Refill fluid supply. Prime pump. Manual
Air in pump or hose Check and tighten all fluid connections.
Intake valve is leaking Clean intake valve. Be sure ball seat is not
Pump packings are worn Replace pump packings. Manual 308798.
Paint is too thick Thin the paint according to the supplier’s
Engine speed is too high Decrease throttle setting before priming pump.
Clutch surfaces are not matched to each other
when new and may cause noise
Reprime pump. Manual 308867.
308867. Check fluid supply often to prevent
running pump dry.
Reduce engine speed and cycle pump as
slowly as possible during priming.
nicked or worn and that ball seats well. Reassemble valve.
recommendations
Manual 308867.
Clutch surfaces need to wear into each other.
Noise will dissipate after a day of run time
Engine stalls
3088706
Engine speed is to slow Increase throttle setting
Adjust engine speed at no load to 3750 –
3850 rpm
Fluid filter is clogged Relieve pressure and clean filter
Too much pump friction (new pump) Reduce pressure to 3000 psi until pump wears
in
Spark plug wire is loose Reconnect wire
Rollers
Removal
1.
2. Fig. 2. Remove six cap screws (10) lock washers
(9) and cover assembly (24).
Note: A screw driver may be needed to pry off
cover assembly.
3. Remove dowel pins (97) and rollers (98)
Installation
1. Install rollers (98) and dowel pins (97)
2. Install cover assembly (24) with six lock washers
(9) and cap screws (10).
Relieve pressure; page 4.
Drive Housing
Removal
1.
2. Fig. 2. Remove six cap screws (10) lock washers
(9) and cover assembly (24).
Relieve pressure; page 4.
20
98
97
9
9
99
24
Fig. 2
Installation
1. Liberally apply bearing grease (supplied with
replacement gear cluster) to gear cluster (18),
washers (82) and (83) and to areas called out by
note 1. Use full 0.68 pint (0.32 liter) of grease for
GMax 7900.
9033A
10
3. Fig. 3. Remove two screws (99) and washers (9).
4. Remove four cap screws (10) lock washers (9)
from drive housing (20).
5. Lightly tap around drive housing (20) to loosen
drive housing. Pull drive housing straight off pinion
housing. Be prepared to support gear cluster (18),
which may also come out.
10
9
1
20h
20g
18
B
82
83
20
9
2. Place bronze colored washer (83) and silver
colored washer (82) onto drive housing (20). Install
gear cluster (18) through washers (83) and (82).
3. Place bronze colored washer (20g) and silver
colored washer (20h) on shaft protruding from
large shaft of drive housing (20). Align gears and
push new drive housing straight onto pinion housing and locating pins (B).
4. Install two washers (9) and screws (99).
5. Install four lock washers (9) and cap screws (10)
into drive housing (20).
6. Install cover assembly (24) with six lock washers
(9) and cap screws (10).
99
1
Apply remaining grease to these areas
Fig. 3
9032A
Cam Follower Bearings
Removal
1.
2. Fig. 16. Cycle pump piston rod (222) to lowest
position. Turn engine off.
3. Fig. 4. Remove six cap screws (10), lock washers
(9) and cover assembly (24).
Note: A screw driver may be needed to pry off
cover assembly.
4. Remove four dowel pins (97) and rollers (98).
5. From front, drive out pump pin (101) with a screw
driver.
6. Remove two retainer rings (20d).
7. Remove cam follower plate (20b).
Note: Two 1/2 in. x 13 bolts may be
needed to remove cam follower plates.
8. Remove two cam follower bearings (20c).
Relieve pressure; page 4.
Installation
1. Install two cam follower bearings (20c).
2. Install cam follower plate (20b).
3. Install two retainer rings (20d).
4. Drive in pump pin (101) until it engages with pump
pin retaining clip (20a).
5. Install four rollers (98) and dowel
pins (97).
6. Install cover assembly (24) with six lock washers
(9) and cap screws (10).
20c
20
98
97
9
10
20a
20b
20d
101
9047A
Fig. 4
24
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