Graco Mark VII Max Repair Manual page 11

TYPE OF PROBLEM
Pump output is low
Motor runs but pump does
not stroke
Excessive paint leakage
into throat packing nut
Fluid is spitting from gun
3A2244A
WHAT TO CHECK
If check is OK, go to next check
Pump rod damage
Low stall pressure
Piston packings are worn or dam-
aged
O-ring in pump is worn or damaged
Intake valve ball is packed with mate-
rial
Pressure setting is too low
Large pressure drop in hose with
heavy materials
Check to see if 10/16 Amp switch is
on 10A setting. Make sure circuit is
able to provide 16A.
Displacement pump pin damaged or
missing; see pump manual.
Connecting rod assembly damaged;
see pump manual.
Gears or drive housing damaged,
page 26.
Throat packing nut is loose
Throat packings are worn or dam-
aged
Displacement rod is worn or dam-
aged
Air in pump or hose
Tip is partially clogged
Fluid supply is low or empty
WHAT TO DO
When check is not OK, refer to this column
Repair pump. See pump manual.
Turn pressure knob fully clockwise. Make sure
pressure control knob is properly installed to
allow full clockwise position. If problem per-
sists, replace pressure transducer.
Replace packings; see pump manual.
Replace o-ring; see pump manual.
Clean intake valve; see pump manual.
Increase pressure; see pump manual.
Use larger diameter hose and/or reduce overall
length of hose.
Switch to 16A setting. Change to circuit that
provides 16A. Change to less loaded circuit.
Replace pump pin if missing. Be sure retainer
spring is fully in groove all around connecting
rod; see pump manual.
Replace connecting rod assembly; see pump
manual.
Inspect drive housing assembly and gears for
damage and replace if necessary; see pump
manual.
Remove throat packing nut spacer. Tighten
throat packing nut just enough to stop leakage.
Replace packings; see pump manual.
Replace rod; see pump manual.
Check and tighten all fluid connections. Cycle
pump as slowly as possible during priming.
Clear tip; see Operation manual.
Refill fluid supply. Prime pump; see pump man-
ual. Check fluid supply often to prevent running
pump dry.
Troubleshooting
11