Graco G40, Instructions - Parts Manual

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Troubleshooting
311052E 17
Troubleshooting
General Troubleshooting
Check all possible remedies in the troubleshooting
charts before disassembling the gun.
Some improper patterns are caused by the
improper balance between air and fluid. Refer to
Spray Pattern Troubleshooting, page 19.
Problem Cause Solution
Fluid leakage through venting holes. Worn packings or needle. Replace needle assembly. (14)
Air leakage through venting hole. Worn o-ring (23) or gasket (15). Check and replace parts as needed.
Air leakage from back of gun. Worn o-rings (22, 23). Replace o-rings.
Air does not trigger. Piston stem is disconnected from
main body of piston assembly (20). Replace piston assembly.
Air does not shut off. Piston assembly not seating properly.
Broken return spring (29).
Swollen o-ring (22).
Worn piston stem o-rings (25, 26).
Bottom gasket (16) failed.
Clean/service piston assembly.
Replace worn or swollen o-rings.
Replace spring.
Replace o-rings.
Replace o-rings.
Replace gasket.
Fluid leakage from front of gun. Fluid needle (14) dirty, worn, or dam-
aged.
Dirty or worn diffuser-seat (10).
Clean or replace fluid needle.
Clean or replace diffuser-seat.
To improve sealing while spraying
lightweight materials and sealing life
while spraying acid catalyzed materi-
als, use optional SST ball and plastic
seat.
Fluid is present at air cap holes. Spray tip is leaking,
Diffuser-seat (10) is insufficiently
tightened.
Verify that retainer (8) or RAC air cap
assembly (30), are tight. If so, replace
spray tip (9).
Tighten diffuser-seat.