Troubleshooting
312798J
25
Troubleshooting
•
Check all possible problems and causes before
disassembling the pump.
•
For all problems related to the electrostatics, see
Troubleshooting in your gun manual.
F
* To determine if the fluid hose or gun is obstructed, relieve the pressure. Disconnect the fluid hose and place a con-
tainer at the pump fluid outlet to catch any fluid. Turn on the air just enough to start the pump. It the pump starts when
the air is turned on, the obstruction is in the hose or gun.
Relieve the pressure before checking or servicing
the equipment.
Problem
Cause
Solution
Pump fails to operate.
Restricted line or inadequate air sup-
ply; closed or clogged valves.
Clear line or increase air supply. Check that
the valves are open.
Obstructed fluid hose or gun; fluid
hose ID is too small.
Open, clear*; use hose with larger ID.
Fluid dried on the displacement rod.
Clean; always stop the pump at the bottom
of its stroke; keep the wet-cup 1/3 filled with
Graco throat seal liquid (TSL).
Dirty, worn, or damaged air motor
parts.
Clean or repair air motor. See manual
312796.
DataTrak models only: Air valve can-
not cycle because solenoid pin is
extended
Enable runaway protection (See DataTrak
Operation, Setup Mode, page 27). Bleed
air from motor. Press
on the DataTrak
display to retract solenoid pin.
Pump operates, but output is
low on both strokes.
Restricted line or inadequate air sup-
ply; closed or clogged valves.
Clear line or increase air supply. Check that
the valves are open.
Obstructed fluid hose or gun; fluid
hose ID is too small.
Open, clear*; use hose with larger ID.
Worn packings in displacement
pump.
Replace packings. See manual 312792.
Pump operates, but output is
low on downstroke.
Held open or worn ball check valves
or piston packings.
Clear valve; replace packings. See manual
312794.
Erratic or accelerated pump
speed.
Exhausted fluid supply.
Refill and prime.
Held open or worn ball check valves
or packings.
Clear valve, replace packings; see manual
312794.
Fluid being pumped is visible
in the TSL reservoir.
Worn throat packings.
Replace throat packings. See manual
312794.
Fluid is visible in the overflow
chamber.
Damaged bellows.
Replace. See manual 312793.
