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Troubleshooting
18 313255F
Troubleshooting
NOTE: Check all possible problems and causes before
disassembling the pump.
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.
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
312794.
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.