Graco GM3500 SPRAYER 231-078 Operation manual

308–709
Rev. B
Supercedes Rev. A
INSTRUCTIONS-PARTS LIST
INSTRUCTIONS
This manual contains important
warnings and information.
READ AND KEEP FOR REFERENCE.
4.0 HORSEPOWER, GASOLINE-POWERED
GM3500 Airless Paint Sprayer
3000 psi (210 bar, 21 MPa) Maximum Working Pressure
Model 231–579, Series A
Basic Sprayer with Lo-Boy Cart
Model 231–077
Same as 231–579, with hose and gun, RAC IVr
DriplesstTip Guard, and 517 size SwitchTipt
Model 231–578, Series A
Basic Upright Sprayer
Model 231-057
Same as 231–578, with hose and gun, RAC IVr
DriplesstTip Guard, and 517 size SwitchTipt
CAUTION
Always use a minimum hose length of 50 foot
(15 m) 1/4 inch ID or 50 foot (15 m) 3/8 inch ID. An
undersized hose may result in poor equipment
performance and damage to the clutch.
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
Graco Inc. is registered to I.S. EN ISO 9001
Model 231-057 Shown
0136C

2 308-709
Table of Contents
Warnings 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component Identification and Function 5. . . . . . . . . . . .
Setup 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fueling 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Startup 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suction Tube Storage 13. . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Control 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump 17. . . . . . . . . . . . . . . . . . . . . . . . . . .
Bearing Housing and Connecting Rod 18. . . . . . . . . . . .
Drive Housing 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pinion, Clutch, Clamp, Field & Engine 20. . . . . . . . . . . .
Pinion Housing 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Field & Wiring Harness 24. . . . . . . . . . . . . . . . . . . . . . . . .
Clamp 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch Housing 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts
Basic Lo-Boy Cart 28. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Upright Sprayer 30. . . . . . . . . . . . . . . . . . . . . . . .
Pinion Assembly 32. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Control 33. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Phone Number 35. . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Warranty 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Symbols
Warning Symbol
WARNING
This symbol alerts you to the possibility of serious
injury or death if you do not follow the instructions.
Caution Symbol
CAUTION
This symbol alerts you to the possibility of damage to
equipment if you do not follow the instructions.
WARNING
INSTRUCTIONS
EQUIPMENT MISUSE HAZARD
Equipment misuse can cause the equipment to rupture or malfunction and result in serious injury.
DThis equipment is for professional use only.
DRead all instruction manuals, tags, and labels before operating the equipment.
DUse the equipment only for its intended purpose. If you are not sure, call your Graco distributor.
DDo not alter or modify this equipment. Use only genuine Graco parts.
DCheck equipment daily. Repair or replace worn or damaged parts immediately.
DDo not exceed the maximum working pressure of the lowest rated system component. Refer to the
Technical Data on page 35 for the maximum working pressure of this equipment.
DUse fluids and solvents which are compatible with the equipment wetted parts. Refer to the Tech-
nical Data section of all equipment manuals. Read the fluid and solvent manufacturer’s warnings.
DDo not use hoses to pull equipment.
DRoute hoses away from traffic areas, sharp edges, moving parts, and hot surfaces. Do not expose
Graco hoses to temperatures above 82_C (180_F) or below –40_C (–40_F).
DDo not lift pressurized equipment.
DComply with all applicable local, state, and national fire, electrical, and safety regulations.
DWear hearing protection when operating this equipment.


WARNING
INJECTION HAZARD
Spray from the gun, leaks or ruptured components can inject fluid into your body and cause extremely
serious injury, including the need for amputation. Fluid splashed in the eyes or on the skin can also
cause serious injury.
Fluid injected into the skin may look like just a cut, but it is a serious injury. Get immediate medi-
cal attention.
Do not point the gun at anyone or at any part of the body.
Do not put your hand or fingers over the spray tip.
Do not stop or deflect leaks with your hand, body, glove or rag.
Do not “blow back” fluid; this is not an air spray system.
Always have the tip guard and the trigger guard on the gun when spraying.
Check the gun diffuser operation weekly. Refer to the gun manual.
Be sure the gun trigger safety operates before spraying.
Lock the gun trigger safety when you stop spraying.
Follow the Pressure Relief Procedure on page 12 if the spray tip clogs and before cleaning,
checking or servicing the equipment.
Tighten all fluid connections before operating the equipment.
Check the hoses, tubes, and couplings daily. Replace worn or damaged parts immediately. Do not
repair high pressure couplings; you must replace the entire hose.
Fluid hoses must have spring guards on both ends, to help protect them from rupture caused by
kinks or bends near the couplings.
TOXIC FLUID HAZARD
Hazardous fluid or toxic fumes can cause serious injury or death if splashed in the eyes or on the skin,
inhaled, or swallowed.
Know the specific hazards of the fluid you are using.
Store hazardous fluid in an approved container. Dispose of hazardous fluid according to all local,
state and national guidelines.
Always wear protective eyewear, gloves, clothing and respirator as recommended by the fluid and
solvent manufacturer.
FUEL HAZARD
The fuel used in this unit is combustible and when spilled on a hot surface can ignite and cause a fire.
Do not fill the fuel tank while the engine is running or hot.
EXHAUST HAZARD
The exhaust contains poisonous carbon monoxide which is colorless and odorless.
Do not operate this equipment in a closed building.

4 308-709
WARNING
FIRE AND EXPLOSION HAZARD
Improper grounding, poor ventilation, open flames or sparks can cause a hazardous condition and
result in a fire or explosion and serious injury.
If there is any static sparking or you feel an electric shock while using this equipment, stop spray-
ing immediately. Do not use the equipment until you identify and correct the problem.
Provide fresh air ventilation to avoid the buildup of flammable fumes from solvents or the fluid
being sprayed.
Keep the spray area free of debris, including solvent, rags, and gasoline.
Disconnect all electrical equipment in the spray area.
Extinguish all open flames or pilot lights in the spray area.
Do not smoke in the spray area.
Do not turn on or off any light switch in the spray area while operating or if fumes are present.
Do not operate a gasoline engine in the spray area.
Ground the sprayer to a true earth ground with the ground wire and clamp (supplied).
Use only electrically conductive hoses.
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.
MOVING PARTS HAZARD
Moving parts can pinch or amputate your fingers.
Keep clear of all moving parts when starting or operating the sprayer.
Before servicing the equipment, follow the Pressure Relief Procedure on page 12 to prevent the
equipment from starting unexpectedly.
Liquidscan be injected into the body by high pressure airless
spray or leaks – especially hose leaks.
Keep body clear of the nozzle. Never stop leaks with any part of the
body. Drain all pressure before removing parts.Avoidaccidental
triggering of gun by always setting safety latch when not spraying.
Never spray without a tip guard.
Incaseofaccidentalskininjection,seekimmediate
“SurgicalTreatment”.
Failure to follow this warning can result in amputation or serious
injury.
FIRE AND
EXPLOSION HAZARD SKIN INJECTION HAZARD
READ AND UNDERSTAND ALL LABELS AND INSTRUCTION MANUALS BEFORE USE
Spraypainting,flushing or cleaning equipment with flammable
liquids in confined areas can result in fire or explosion.
Use outdoors or in extremely well ventilated areas. Ground
equipment,hoses, containersandobjectsbeingsprayed.
Avoid all ignition sources such as static electricity from plastic
drop cloths, open flames such as pilot lights, hot objects such as
cigarettes, arcs from connecting or disconnecting power cords
or turning light switches on and off.
Failure to follow this warning can result in death or serious injury.
NOTE: This is an example of the DANGER label on your sprayer. This label is available in other languages, free of
charge. See page 34 to order.

5308-709
06905
C
Fig. 1
E
F
D
A
G
MB
H
R
T
P
S
U
NJ
K
Component Identification and Function
L
VW
0015A
0016A
APressure Control Switch ON/OFF, enables/disables clutch function
BPressure Adjusting Knob Controls fluid outlet pressure
CAir Cleaner* Filters air entering the carburetor
DFuel Tank* Holds 0.66 gallons (2.5 liters) of [(R+M)/2]; 86 octane gasoline
EMuffler* Reduces noise of internal combustion
FSpark Plug Cable* Routes electrical current to spark plug
GFuel Valve* On/off valve to regulate fuel flow from gasoline tank to carburetor
HChoke* Enriches air/gasoline mixture for cold starting
JThrottle* Adjusts engine speed for large or small orifice spray tips
KEngine Switch* Enables/disables engine operation
LSecondary Fluid Outlet Secondary Hose and spray gun are connected here
MPressure Control Controls clutch cycling to maintain fluid pressure.
NEngine* 4.0 HP gasoline engine
PClutch Transfers power from engine to drive assembly
RDrive Assembly Transfers power from clutch to displacement pump
SDisplacement Pump Provides fluid to be sprayed through spray gun
TFluid Filter Filters fluid between source and spray gun
UGrounding Clamp and Wire Grounds sprayer system
VPressure Drain Valve Relieves fluid pressure when open
WPrimary Fluid Outlet Hose and spray gun are connected here
*For more detailed explanations of these controls, refer to the Honda engine manual; supplied

6 308-709
Setup
WARNING
If you supply your own hoses and spray gun, be
sure the hoses are electrically conductive, that the
gun has a tip guard, and that each part is rated for
at least 3000 psi (210 bar, 21 MPa) Maximum
Working Pressure . This is to reduce the risk of
serious bodily injury caused by static sparking, fluid
injection or over-pressurization and rupture of the
hose or gun.
CAUTION
To avoid damaging the pressure control, follow these
precautions.
1. Always use nylon spray hose at least 50 ft (15.2
m) long.
2. Never use a wire braid hose; it is too rigid to act
as a pulsation dampener.
3. Never install a ball valve or shutoff device be-
tween the filter and the 50 ft (15 m) hose.
4. Always use the main filter outlet for one gun op-
eration. Never plug this outlet.
1. Connect hose and gun. Remove the plastic cap
plug from the 1/4 npsm(m) outlet nipple (W).
Assemble the 50 ft (15 m) hose (121), 3 ft (0.9 m)
whip hose (122) and gun (123), and connect them
to the outlet nipple.
2. DO NOT use thread sealant on the hose and gun
connections. DO NOT install the spray tip until the
system is primed.
3. Two gun hookup. Unscrew the cap (L) from the
secondary hose outlet. Connect an accessory
hose and gun to the 1/4 npsm(m) nipple.
4. Fill the packing nut/wet-cup (216) 1/3 full with
Graco Throat Seal Liquid (TSL), supplied, and
keep it filled, to help extend the pump life.
Fig. 2 06882
121
122
123
216
L
W


Setup
5. Check the engine oil level. Refer to the Honda
engine manual, supplied. This is a summary of the
information: Remove one of the oil fill plugs; (C)
the oil should be almost overflowing. See Fig. 3.
Add oil as necessary.
Recommended lubrication oil: Use a high–quality,
detergent oil, SAE 10W–40, classified “FOR
SERVICE SE or SF”, for regular use and for
breaking–in a new engine.
6. Be sure your system is properly grounded
before operating it. Read and follow the warning
section, Fire Or Explosion Hazard, page 4. Use
the ground wire (47) provided.
7. Fill the gas tank. See the Fueling section, below.
8. Flush the pump to remove the lightweight oil
which was left in the pump to protect it from rust.
Refer to the Flushing, page 12.
9. Prepare the paint according to the manufacturer’s
recommendations. Remove any skin that may
have formed. Stir the paint to mix pigments.
10. Strain the paint through a fine nylon mesh bag
(available at most paint dealers) to remove par-
ticles that could clog the filter or spray tip. This is
probably the most important step toward trouble–
free spraying.
11. Keep the sprayer upright and level during
operation and whenever it is being moved. Read
the last CAUTION on page 10.
06906A
A
Fig. 3
47
B
C

 
Fueling
WARNING
Gasoline is extremely flammable and explosive
under certain conditions. To reduce the risk of a fire
or explosion:
Always shut off the engine (B) before refueling.
Refuel in a well–ventilated area.
Do not smoke or allow flames or sparks in the
area where the engine is refueled or where the
gasoline is stored.
Do not overfill the tank. Make sure the filler cap
is securely closed after refueling.
Be careful not to spill fuel when fueling. Fuel
vapor or spilled fuel can ignite. If any fuel is
spilled, make sure the area is dry before starting
the engine.
1. Fuel specifications. Use automotive gasoline
with a pump octane number of 86 or higher. If the
engine knocks or pings, use a higher octane
gasoline. Unleaded fuel minimizes combustion
chamber deposits.
2. Gasolines containing alcohol (gasohol). Do not
use gasohol which contains methanol, if the gaso-
hol does not contain cosolvents and corrosion
inhibitors for methanol. Even if it does contain such
additives, do not use the gasohol if it contains
more than 5% methanol.
NOTE: The HONDA engine warranty does not cover
damage resulting from the use of gasolines containing
alcohol. See the HONDA engine manual for more
information.
3. General. Do not use oil and gasoline mixtures or
contaminated gasoline. Avoid getting dirt, dust or
water in the fuel tank.
4. Tank Capacity. 0.66 gallons (2.5 liter). Always
leave at least 1/2 in. at the top of the tank for
expansion.
5. Shut off the engine before refueling.
6. After refueling, tighten the fuel tank cap (A)
firmly.


Startup
NOTE: Refer to Fig. 1 as you start the sprayer.
NOTE: When starting a sprayer that IS NOT PRIMED,
remove the spray tip.
1. Be sure the gas tank is full. Open the black fuel
shutoff lever (G).
2. Check the engine oil level.
NOTE: The engine stops automatically if it is low on
oil. If you try to start it again without adding more oil, a
red light on the rear of the engine glows as you pull the
starter rope.
3. Place the suction tube (S) into the paint
container.
4. Turn the pressure control switch (A) to OFF.
5. Open the black fuel shutoff lever (G) by pushing
it in the direction of the arrow.
6. Be sure the spark plug cable (F) is firmly
pushed onto the spark plug.
CAUTION
Never attempt to start the engine unless fluid pres-
sure is relieved and the pressure control is turned
OFF. Attempting to start the engine when it is pres-
surized will damage the recoil system.
7. To start the engine:
a. Turn the pressure adjusting knob (B) all the
way counterclockwise to the lowest pressure
setting.
b. Pull the metal throttle lever (J) away from
the fuel tank to the maximum position (fully
left).
c. If the engine is cold, close the gray choke
lever (H), located beneath the air cleaner.
If the engine is warm, close the choke only
half way or not at all.
d. Turn the engine switch to ON.
WARNING
A rope which recoils too quickly may hit someone
and cause serious bodily injury. The rope could
also jam in the recoil assembly.
e. Grasp the starter rope. Holding the frame of
the sprayer with one hand, pull the rope rapidly
and firmly. Continue holding the rope as you
let it return. Pull and return the rope until the
engine starts.
f. Open the choke (H) as soon as the engine
starts. In cold weather, leave the choke closed
for 10 to 30 seconds before opening it to keep
the engine running.
8. Disengage the gun safety latch. See Fig. 4.

10 308-709
Startup
9. To start the pump:
a. Open the pressure drain valve (V).
b. Turn the pressure control switch (A) to ON.
c. Slowly increase the pressure knob (B) until the
pump starts to cycle slowly. Cycle the pump
slowly until fluid is flowing smoothly from the
pressure drain valve, indicating the pump is
fully primed.
d. Close the pressure drain valve (V).
e. Hold a metal part of the gun firmly against a
grounded metal container, squeeze the trigger
until fluid is flowing smoothly from the gun.
f. Release the trigger and engage the gun
safety latch.
WARNING
To reduce the risk of serious bodily injury from fluid
injection, NEVER operate the spray gun with the tip
guard removed.
10. Install the spray tip. Refer to the instruction
manual supplied with the tip (307–848 if you are
using a RAC IV).
11. Adjust the engine speed and pump pressure.
Trigger the gun onto a test paper to check the
spray pattern and atomization. Turn the pressure
adjusting knob (B) until you get a good pattern.
Then slowly lower the throttle (J) setting as far as
you can without changing the spray pattern.
CAUTION
Always use the lowest needed fluid pressure and the
lowest needed throttle (J) setting, to increase the life
of the sprayer. Higher settings cause excessive
clutch cycling, premature tip wear and premature
pump wear.
CAUTION
Close the fuel valve (G) when transporting thesprayer
to prevent fuel from flooding the engine.
Keep the sprayer upright and level when operating it
and when transporting it. This prevents crankcase oil
from leaking into the combustion chamber, which
makes start up very difficult.
Fig. 4
Gun safety latch shown
engaged
Gun safety latch shown
disengaged
0137
1
2
1
2

11308-709
Maintenance
WARNING
To reduce the risk of serious bodily injury always
follow the Pressure Relief Procedure Warning on
page 12 before checking, adjusting, cleaning or
shutting down the sprayer.
CAUTION
For detailed engine maintenance and specifications,
refer to the separate engine manual.
DAILY: Check the engine oil level and fill as
necessary.
DAILY: Check and fill the gas tank.
AFTER THE FIRST 20 HOURS OF OPERATION
AND EACH 100 HOURS THEREAFTER: Change the
oil.
WEEKLY: Remove the air filter cover and clean the
element. In very dusty environments, check the filter
daily. Replace the element as needed. Replacement
elements can be purchased from your local HONDA
dealer.
WEEKLY: Check the level of the TSL in the displace-
ment pump packing nut. Fill the nut, if necessary. Keep
TSL in the nut to help lubricate the pump packings.
SPARK PLUG: Use only a BPR6ES (NGK) or W20
EPR–U (NIPPON DENSO) plug. Gap the plug to 0.028
to 0.031 in. (0.7 to 0.8 mm). Always use a spark plug
wrench.

12 308-709
Pressure Relief Procedure
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,
install or clean the spray tip.
1. Engage the gun safety latch.
2. Turn the engine switch to OFF.
3. Move the pressure control ON/OFF switch to OFF.
4. Disengage the gun safety latch. Hold a metal part
of the gun firmly to a grounded metal pail. Trigger
the gun to relieve pressure.
5. Engage the gun safety latch.
6. Open the pressure drain valve. Leave the pressure
drain valve open until you are ready to spray
again.
7. Disconnect the spark plug cable.
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, VERY SLOWLY
loosen the tip guard retaining nut or hose end coupling
to Relieve the pressure gradually, then loosen com-
pletely. Now clear the tip or hose.
Flushing
NOTE: Several flushes are often required to thoroughly clean the system and prepare it for the next fluid to be
sprayed, or to store the sprayer. Use this chart to determine the required flushing order for the fluid you are using,
and then follow the procedure below for flushing.
*Use this category for flushing a brand new sprayer and flushing after storage.
System has
this fluid in it:
Next fluid to be
s
p
rayed
Flushing order: Before you spray or store
s
p
rayer:
t
hi
s
fl
u
id
i
n
i
t: spraye
d
.Flush 1 Flush 2 Flush 3 sprayer:
*Oil-based
solvent or paint Oil-based paint – new color Mineral spirits none none Prime with oil-based paint
Oil-based
solvent or paint Water-based paint Mineral spirits Warm soapy water Clean water Prime with water-based paint
Oil-based
solvent or paint Prepare for storage Mineral spirits none none Relieve pressure, Leave drain valve open
Water or water-
based paint Water-based paint – new color Warm soapy water Clean water none Prime with water
Water or water-
based paint Oil-based paint Warm soapy water Clean water Mineral spirits Prime with oil
Water or water-
based paint Prepare for storage Warm soapy water Clean water Mineral spirits Relieve pressure, Leave drain valve open

13308-709
Flushing
CAUTION
NEVER allow water to freeze in the pressure control.
Doing so prevents the sprayer from being started and
causes serious damage to the pressure control. Pump
the water out with mineral spirits.
WARNING
FIRE AND EXPLOSION HAZARD
To reduce the risk of static sparking and
splashing when flushing, always remove
the spray tip from the gun and hold a
metal part of the gun firmly to the side of a
grounded metal pail.
1. Follow the Pressure Relief Procedure on page
12. Engage the gun safety latch.
2. Turn the pressure adjusting knob fully counter-
clockwise to the minimum pressure.
3. Remove the spray tip from the gun. Remove the
filter bowl (A) and screen (B); see manual
307–273. Clean the screen separately and install
the bowl without the screen to flush it. See Fig. 5.
4. Put the suction tube into a grounded metal pail
with 1/2 gallon of compatible solvent.
5. Start the sprayer. See page 10. To save the fluid in
the sprayer, trigger the gun into another container
until the next fluid appears, then trigger the gun
back into the fluid you are pumping. Circulate the
flushing fluid to thoroughly clean the system.
6. Remove the strainer (and suction tube, if used) and
clean separately to remove all paint sediment.
7. Do not run the pump dry for more than 30 seconds
to avoid damaging the pump packings!
8. Follow the Pressure Relief Procedure on page
12. Engage the gun safety latch.
9. Unscrew the filter bowl and reinstall the clean
screen. Install the bowl and hand tighten. Install
the suction tube assembly.
Fig. 5
A
B
C
53
06878
Suction Tube Storage
Place the suction tube in the receptacle on the cart
frame as shown in Fig. 6.
Fig. 6 06970

14 308-709
Troubleshooting
WARNING
To reduce the risk of serious bodily injury always
follow the Pressure Relief Procedure Warning on
page 12 before checking, adjusting, cleaning or
shutting down the sprayer.
Check everything in the chart before disassembling the sprayer. (Continued on page 15)
PROBLEM CAUSE SOLUTION
Engine/sprayer won’t start Engine switch not on Turn on.
Out of gas Replenish
Engine oil level low Try starting engine. If light on rear of en-
gine glows, replenish oil.
Spark plug cable disconnected or
spark plug damaged Connect cable on top of engine or re- place spark plug. See Fig. 1, page 5.
Water frozen in pressure control Return pressure control to authorized
Graco dealer for repair.
Engine won’t “pull over” Oil seepage into combustion
chamber Remove spark plug. Pull starter rope 3 or 4 times. Clean and replace plug. Try to
start. Keep sprayer upright to avoid oil
leakage. See last CAUTION on page 10.
Engine operates, but dis-
placement pump doesn’t Pressure control switch turned OFF Turn on.
Pressure setting too low Increase pressure.
Displacement pump outlet filter
dirty Clean filter.
Tip or tip filter clogged Clean tip or tip filter.
Displacement pump rod seized by
dry paint Service pump. See page 18.
Connecting rod worn or damaged Replace. See page 18.
Drive housing worn or damaged Replace. See page 19.
Electrical power not energizing field Check wiring connections. See pages 16
and 33.
With pressure control switch ON and
pressure turned to MAXIMUM, use a test
light to check continuity across black and
white wires from pressure control.
Have pressure control checked by autho-
rized Graco dealer.
Clutch worn or damaged Service. See page 24.
Pinion assembly worn or damaged Service. See page 20.

15308-709
Troubleshooting
PROBLEM CAUSE SOLUTION
Displacement pump output
low on upstroke Pump inlet screen clogged Clean.
Piston ball check not seating Service piston ball check. See page 18.
Piston packings worn or damaged Replace packings. See page 18.
Sleeve gasket in displacement
pump worn or damaged Replace. See page 18.
Displacement pump output
low on downstroke or both
strokes
Pump inlet screen clogged Clean.
Piston packings worn or damaged Replace packings. See page 18.
Intake valve ball check not seating
properly Clean and service. See page 18.
Engine RPM too low Increase throttle setting. See Startup,
Step 11, page 10.
Clutch worn or damaged Replace. See page 24.
Paint leaks into wet–cup Loose wet–cup Tighten just enough to stop leakage.
Throat packings worn or damaged Replace packings. See page 18.
Displacement rod worn or
damaged Replace rod. See page 18.
Low fluid delivery Pump inlet screen clogged. Clean.
Pressure setting too low Increase pressure. See Startup,
Step 11, page 10.
Engine RPM too low Increase throttle setting. See Startup,
Step 11, page 10.
Dirty outlet filter, tip filter or tip Clean.
Large pressure drop in hose Use larger diameter hose.
Spitting from gun Air in fluid pump or hose Check for loose connections at pump in-
take and tighten. Them prime the pump.
See Startup, page 10.
Tip partially clogged Clear.
Fluid supply is low or empty Refill and prime the pump. See Startup,
page 10. Check fluid supply often to pre-
vent running the pump dry.

16 308-709
Pressure Control Replacement
WARNING
INJECTION HAZARD
To reduce the risk of serious injury,
whenever you are instructed to relieve
pressure, follow the Pressure Relief
Procedure on page 12.
1. Relieve pressure.
2. Disconnect the pressure control while holding the
fitting or elbow (A) firmly. See the CAUTION,
below. See Fig. 7.
CAUTION
Do not allow the elbow or fitting (A) to turn when
removing or connecting the hoses. Turning the
fitting or elbow can shift the calibration of the pres-
sure control.
3. Remove the four mounting screws and washers
(302, 303, 304) from the pressure control cover
(76). See Fig. 8.
4. Carefully remove the pressure control cover (76)
so as not to stress the cables.
5. Disconnect the black and white wires of the pres-
sure control cable (314) from the pressure control
cover.
6. Disconnect the potentiometer cable assembly
(310) from the pressure control cover.
7. Disconnect the red power lead (B) from the
ON/OFF switch.
8. Loosen the ground terminal screw (317) and
disconnect the ground lead (C).
9. Pull off the pressure control cover.
Fig. 7
59
76 TO
FIL-
TER
A
A
Tothe pump.

To the filter.

06873
06873
06872A
Fig. 8
304
BC
302
304
303
317
310
314
76
WARNING
Do not attempt to adjust or calibrate the pressure
control. If the pressure control is faulty, replace it.
10. Reassemble in the reverse order; attach ground
wire (C), power lead (B), and the black and white
connectors. Attach the pressure control cover (76)
using the four mounting screws and washers (302,
303, 304).

17308-709
Displacement Pump
WARNING
To reduce the risk of serious bodily injury always
follow the Pressure Relief Procedure Warning on
page 12 before checking, adjusting, cleaning or
shutting down the sprayer.
Removing the pump See Fig. 9.
1. Flush the pump. Relieve pressure.
2. Hold the intake valve (223) with a wrench and un-
screw the suction tube (30). Remove the hose (55).
For upright carts, remove the spring clips (90,92)
and drain hose (91).
3. Push the retaining spring (26) up. Push the pin (25)
out the rear.
4. Loosen the locknut (27). Unscrew the pump.
Fig. 9
21
26
25
27 55
223
224
204*
219
220
221*
202*
83
92
91
90
30
01200A
Repairing the pump
See Displacement Pump manual 307–806 for pump
repair procedures.
WARNING
Seat the retaining spring (26) firmly in theconnecting
rodgroovetopreventthepin(25)fromworkingloose
due to vibration.
If the pin works loose, it or other parts could break off
duetotheforceofthepumpaction.Thesepartscould
be projected through the air and result in serious
injury or property damage, including the connecting
rod and bearing housing.
Installing the pump
1. Screwthepump3/4ofthewayintothebearinghous-
ing(21).Holdthepin(25)uptothepinholeinthecon-
necting rod (22) and continue screwing in the pump
until the pin slides easily into the hole.
2. Align the top threads of the pump cylinder flush with
the face of the bearing housing and so the outletnip-
ple (83) is straight back.
3. Push the retaining spring (26) into the groove of the
connecting rod, all the way around. Torque the lock-
nut (27) to 90 "5 ft-lb (120 "7 Nm).
4. Tighten the packing nut (216) only enough to stop
leaking. Fill the nut 1/2 full with Graco TSL.
5. Assemble the remaining parts.
Fig. 10
25
26
27
22
21
0031A
1
2
Face of bear-
ing housing
Torque
to 90 "5ft-lb
(120 "7 Nm)
2
1
216

18 308-709
Bearing Housing and Connecting Rod
WARNING
To reduce the risk of serious bodily injury always
follow the Pressure Relief Procedure Warning on
page 12 before checking, adjusting, cleaning or
shutting down the sprayer.
NOTE: Steps 1 to 10 refer to Fig. 11.
1. Remove the pump. See page 17.
2. Remove the four screws (69) and lockwashers
(70) from the bearing housing (21).
3. While pulling the connecting rod assembly (22)
with one hand, lightly tap the lower rear of the
bearing housing (21) with a plastic mallet to loosen
it from the drive housing (20). Pull the bearing
housing and the connecting rod assembly off the
drive housing.
4. Inspect the crank (A) for excessive wear and
replace parts as needed.
5. Evenly lubricate the inside of the bronze bearing
(C) in the bearing housing (21), and the inside of
the connecting rod link (D), with high-quality motor
oil. Liberally pack the roller bearing (E) in the
connecting rod assembly (22) with bearing grease.
6. Assemble the connecting rod (22) and bearing
housing (21).
7. Clean the mating surfaces of the bearing and drive
housings.
8. Align the connecting rod with the crank (A). Align
the locating pins (F) in the drive housing (20) with
the holes in the bearing housing (21). Push the
bearing housing onto the drive housing or tap it
into place with a plastic mallet.
CAUTION
Use only the locating pins (F) to align or seat the
bearing housing (21) with the drive housing (20).
9. Install the screws (69) and lockwashers (70) on the
bearing housing. Tighten the screws evenly to 300
"20 in-lb (34 "2.3 Nm).
10. Install the pump. See above.
Fig. 11
69,70
F
C
55
26
83
27
28
30
24
11
A
21
E
D
22
25
64
92
91
90
20
1Torqueto 300 "20in-lb
(34 "2.3 Nm)
1
0149B

19308-709
Drive Housing
WARNING
To reduce the risk of serious bodily injury always
follow the Pressure Relief Procedure Warning on
page 12 before checking, adjusting, cleaning or
shutting down the sprayer.
NOTE: Refer to Fig. 12 for this procedure.
1. Remove the front cover (23).
2. Disconnect the hose (55) from the pump nipple
(83). For the upright carts only, detach the drain
hose (91) from the pump.
3. Remove the four screws (69) and lockwashers
(70) from the bearing housing (21).
4. Lightly tap the back of the bearing housing with a
plastic mallet. Pull the pump, bearing housing and
connecting rod away from the drive housing as
one assembly.
5. Remove the two screws (24) and lockwashers
(11). Remove the four screws (10) and
lockwashers (11).
6. Lightly tap around the drive housing (20) with a
plastic mallet to loosen it from the pinion housing
(19n).
CAUTION
DO NOT drop the gear cluster (18) when removing
the drive housing (20). The gear cluster is easily
damaged. The gear may stay engaged in either the
drive housing or the pinion housing.
DO NOT lose the thrust balls (20c and 19j) located at
each end of the gear cluster. The balls, which are
heavily covered with grease, usually stay in the shaft
recesses, but they could be dislodged. If they are
caught between the gears and not removed, the balls
will seriously damage the drive housing. If the balls
are not in place, the bearings will wear prematurely.
7. Liberally apply bearing grease (20d, supplied) to
the gear cluster (18). Be sure the thrust balls (20c
and 19j) are in place.
8. Place the bronze colored washer (20a) and then
the silver-colored washer (20b) on the shaft pro-
truding from the big bearing of the drive housing
(20). Align the gears and push the new drive
housing straight onto the pinion housing and
locating pins (B).
9. Starting at Step 5, work backwards to reassemble
the sprayer. Or, move ahead to the next section in
this manual if further service is needed.
Fig. 12
10
11
19j
18
20c
11
24
64
23
22
20
20a 20b 19n
11 10
B
70
69
83
21
91
55
0170A
1
1Torqueto 300 "20in-lb
(34 "2.3 Nm)

20 308-709
Pinion, Clutch, Clamp, Field & Engine
Disassembling these parts can start from the pinion
housing or from the clutch, if no pinion service is
needed.
If starting from the pinion housing, first follow Steps
1 to 6 of Drive Housing, on page 19, and then
continue with the procedure below.
If starting from the clutch, see page 22.
Pinion Housing
Removing the Pinion Housing
WARNING
To reduce the risk of serious bodily injury always
follow the Pressure Relief Procedure Warning on
page 12 before checking, adjusting, cleaning or
shutting down the sprayer.
NOTE: Refer to Fig. 13 for Steps 1 to 3, except where
noted.
1. Remove the two bottom screws (10) first, and then
remove the top three screws (10).
2. Pull the pinion housing (19n) away from the clutch
housing (2). The armature (4a) will come with it.
3. Pull out the armature (4a).
CAUTION
Do not lose the thrust ball (19j). Refer to the CAU-
TION on page 19 for more information.
NOTE: To disassemble the pinion, continue with
Repairing the Pinion, page 21. To disassemble more
of the sprayer, go to page 22. To reassemble the
sprayer from this point, skip ahead to Reassembly,
page 27, Step 7.
Fig. 13
19j
4a
1110
2
11 10
19n
0171A