Graco ultimate mx ii, Repair Manual

Page: 12 / 48

Troubleshooting
12 311365H
Pump output is low 14. O-ring in pump is worn or dam-
aged
14. Replace o-ring; see pump manual 310643
or 310894.
15. Intake valve ball is packed with
material
15. Clean intake valve; see pump manual
310643 or 310894.
16. Pressure setting is too low 16. Increase pressure; see pump manual
310643 or 310894.
17. Large pressure drop in hose with
heavy materials
17. Use larger diameter hose and/or reduce
overall length of hose. Use of more than
100 ft of 1/4 in. hose significantly reduces
performance of sprayer. Use 3/8 in. hose
for optimum performance (50 ft minimum).
Motor runs but pump does
not stroke 1. Displacement pump pin (32)
damaged or missing; see pump
manual 310643 or 310894. 1. Replace pump pin if missing. Be sure
retainer spring (31) is fully in groove all
around connecting rod; see pump manual
310643 or 310894.
2. Connecting rod assembly (43)
damaged; see pump manual
310643 or 310894. 2. Replace connecting rod assembly; see
pump manual 310643 or 310894.
3. Gears or drive housing damaged,
page 34. 3. Inspect drive housing assembly and gears
for damage and replace if necessary; see
pump manual 310643 or 310894.
Excessive paint leakage into
throat packing nut 1. Throat packing nut is loose 1. Remove throat packing nut spacer.
Tighten throat packing nut just enough to
stop leakage.
2. Throat packings are worn or
damaged 2. Replace packings; see pump manual
310643 or 310894.
3. Displacement rod is worn or
damaged 3. Replace rod; see pump manual 310643 or
310894.
Fluid is spitting from gun 1. Air in pump or hose 1. Check and tighten all fluid connections.
Reduce engine speed and cycle pump as
slowly as possible during priming.
2. Tip is partially clogged 2. Clear tip; see tip guard manual 309640.
3. Fluid supply is low or empty 3. Refill fluid supply. Prime pump; see pump
manual 310643 or 310894. Check fluid
supply often to prevent running pump dry.
Pump is difficult to prime 1. Air in pump or hose 1. Check and tighten all fluid connections.
Reduce engine speed and cycle pump as
slowly as possible during priming.
2. Intake valve is leaking 2. Clean intake valve. Be sure ball seat is not
nicked or worn and that ball seats well.
Reassemble valve.
3. Pump packings are worn 3. Replace pump packings; see pump man-
ual 310643 or 310894.
4. Paint is too thick 4. Thin the paint according to the supplier’s
recommendations.
No display, sprayer operates 1. Display is damaged or has bad
connection 1. Check connections. Replace display.
TYPE OF PROBLEM
WHAT TO CHECK
If check is OK, go to next check
WHAT TO DO
When check is not OK, refer to this column