Graco GM 3500 Instructions-Parts List Manual page 14

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