Troubleshooting - Graco Compact Twin Flow Manual

Troubleshooting

Pumping (after satisfactory startup)
Problem
Pump stalling and no material
being pumped despite
adequate input pressure.
Pumps cycling satisfactorily
but
total material output dropped
off, or one pump output lags
behind the other.
Pumps not discharging normal
or full volume.
Pumps not cycling at all or
pumps not completely cycling.
Pumps drawing material back
down from hose.
Cause
Blocked mixer.
Closed outlet ball valves.
Blocked check valve.
One pump metering
incorrectly.
Low material level in
reservoirs.
Air in material (normally only
high viscosity material).
Piston worn or broken.
Check valve malfunction.
Flow controls set differently
Air circuit failure.
Check valve stuck open.
38
Solution
Turn off air supply and remove
hoses from mixer. Check
hoses for flow.
Open ball valves
Unlikely to be fully restricted,
but possible. Dismantle, clean,
and reinstall.
Check both outputs from the
hoses. If pumps are out of
phase or if one pump is not
discharging a full shot of
material, see next solution.
Refill reservoirs. Prime pump
and hoses.
Reload reservoir with
minimum air entrapment. (Ask
for technical advice.) See "air
in hose" solution.
Remove and inspect
suspected piston. Replace if
worn, damaged.
Remove, clean, and reinstall
the check valve.
Readjust flow controllers.
See Logic Circuit
troubleshooting.
Remove check valve and
clean or replace.