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308200 11
Troubleshooting
WARNING
To reduce the risk of serious injury whenever you
are instructed to relieve pressure, always follow the
Pressure Relief Procedure on page 8.
1. Relieve the pressure.
2. Check all possible problems and causes before
disassembling the pump.
PROBLEM
CAUSE SOLUTION
Pump fails to operate. Restricted line or inadequate air supply Clear*; see Technical Data on pages 24–27.
Obstructed fluid hose or gun/valve;
fluid hose ID is too small.
Clear*; use a hose with a larger ID.
Fluid dried on the displacement rod. Clean; see Service on pages 12–19.
Dirty or worn air motor parts. Clean or repair; see separate air motor manual.
Pump operates, but
output is low on both
strokes.
Restricted line or inadequate air supply. Clear*; see Technical Data on pages 24–27.
Obstructed fluid hose or gun/valve;
fluid hose ID is too small.
Clear*; use a hose with a larger ID.
Bleeder valve is open. Close.
Air is leaking into the supply container. Check wiper plate seal.
Fluid is too heavy for pump priming. Use bleeder valve (see page 9); use wiper plate
with ram or pneumatic elevator cart.
Worn packings in displacement pump. Replace packings.
Pump operates, but
output is low on down-
stroke.
Fluid too heavy for pump priming. Use bleeder valve (see page 9); use wiper plate
with ram or pneumatic elevator cart.
Held open or worn intake valve or seals. Clear valve; replace seals.
Pump operates, but
output is low on up-
stroke.
Held open or worn piston valve or seals. Clear valve; replace seals.
Erratic or accelerated
pump speed.
Exhausted fluid supply. Refill and prime.
Fluid is too heavy for pump priming. Use the bleeder valve (see page 9); use wiper
plate with ram or pneumatic elevator cart.
Held open or worn piston valve or seals. Clear valve; replace seals.
Held open or worn priming piston. Clear; service.
Worn packings in displacement pump. Replace packings.
* To determine if the fluid hose or gun is obstructed, follow the Pressure Relief Procedure on page 8. Disconnect
the fluid hose and place a container at the pump fluid outlet to catch any fluid. Turn on the air just enough to start
the pump (about 20–40 psi [0.14–0.3 MPa, 1.4–2.8 bar]). If the pump starts when the air is turned on, the obstruc-
tion is in the fluid hose or gun.
NOTE: If you experience air motor icing, contact your Graco distributor for assistance.