Troubleshooting
14
3A0732U
Troubleshooting
NOTE:
Check all possible problems and causes before
disassembling the pump.
Relieve the pressure
before checking or servicing
the equipment.
Problem
Cause
Solution
Air motor will not run.
Damaged air valve (214).
Replace or service air valve (214).
See page 19.
Damaged pilot valve (213).
Replace pilot valves (213). See page
22.
Air continuously exhausting
around air motor piston rod.
Damaged u-cups (207).
Replace piston rod u-cups (207).
See page 24.
Air continuously exhausting from
muffler.
Damaged air valve plate (305) or cup
(312).
Replace or service air valve (214).
See page 19.
Air motor “bounces” at top of
stroke.
Damaged bottom pilot valve (213).
Replace bottom pilot valve (213).
See page 22.
Air motor “bounces” at bottom of
stroke.
Damaged top pilot valve (213).
Replace top pilot valve (213). See
page 22.
Icing inside motor.
Air motor operating at high pressure
or high cycle rate.
Reduce pressure, cycle rate, or duty
cycle of motor.
Reduce dew point of compressed
air in moisture coalescing filter.
Pump fails to operate.
Restricted line or inadequate air
supply; 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
(119).
Clean; keep the packing nut
wet-cup filled with Graco throat seal
liquid (TSL).
Pump operates but does not
prime.
Held open or worn ball check valves
or piston packings.
Clear valve; replace packings. See
page 17.
Worn suction hose o-ring (38).
Replace suction hose o-ring (38).
Pump operates, but output is low
on both strokes.
Restricted line or inadequate air
supply; 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 page 17.
