Graco LP 555 Operation - Repair - Parts page 29

Problem
Fluid is spitting from gun
Pump is difficult to prime
Sprayer operates for 5 to 10 minutes
then stops
3A4203B
What to Check
If check is OK, go to next
check
Air in pump or hose.
Spray tip is partially clogged.
Fluid supply is low or empty.
Air in pump or hose.
Intake valve is leaking.
Pump packings are worn.
Paint is too thick.
Pump packing nut too tight. When
pump packing nut is too tight the
packings on the pump rod restrict
pump action and overloads the motor.
Troubleshooting
What to Do
When check is not OK,
refer to this column
Check and tighten all fluid
connections. Cycle pump as slowly as
possible during priming.
Clear tip. See Cleanup, page 23.
Refill fluid supply. Prime pump. See
pump manual. Check fluid supply
often to prevent running pump dry.
Check and tighten all fluid
connections. Cycle pump as slowly as
possible during priming.
Clean intake valve. Be sure ball seat
is not nicked or worn and that ball
seats well. Reassemble valve.
Replace pump packings. See pump
manual.
Thin the paint according to supplier
recommendations.
Loosen pump packing nut. Check for
leaks around throat. If necessary,
replace pump packings. See Pump
manual.
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