Troubleshooting; Mechanical/Fluid Flow - Graco Mark IV 249636 Operation - Repair - Parts

Troubleshooting

PROBLEM
Low or No Fluid/Pressure Output
Motor runs but pump does not stroke
311287A
Relieve pressure; page 5.

Mechanical/Fluid Flow

CAUSE
1 Spray tip worn
2 Spray tip clogged
3 Paint supply
4 Intake strainer clogged
5 Intake valve ball and piston ball are not
seating properly
6 Filter clogged
7 Prime valve leaking
8 Verify pump does not continue to stroke
when gun trigger is released. (Prime valve
not leaking.)
9 Leaking around throat packing nut which
may indicate worn or damaged packings.
See page 27.
10 Pump rod damage
11 Low stall pressure
1 Displacement pump pin damaged or
missing, page 27
2 Connecting rod assembly damaged,
page 30
3 Gears or drive housing damaged,
page 30
Troubleshooting
SOLUTION
1 Follow Pressure Relief Procedure
Warning, then replace tip. See your
separate gun or tip manual.
2 Relieve pressure. Check and clean spray
tip.
3 Refill and reprime pump
4 Remove and clean, then reinstall; or do
not use strainer
5 Remove intake valve and clean. Check
balls and seats for nicks; replace if
necessary, page 27. Strain paint before
using to remove particles that could clog
pump.
6 Relieve pressure. Check and clean filter;
or do not use filter.
7 Relieve pressure. Repair prime valve.
8 Service pump. See page 27.
9 Replace packings, page 27. Also check
piston valve seat for hardened paint or
nicks and replace if necessary. Tighten
packing nut/wet-cup.
10 Repair pump, page 27
11 Do either or both:
a Turn pressure control knob fully
clockwise. Make sure pressure control
knob is properly installed to allow full
clockwise position.
b Try a new pressure transducer.
1 Replace pump pin if missing. Be sure
retainer spring is fully in groove all around
connecting rod, page 27.
2 Replace connecting rod assembly,
page 30
3 Inspect drive housing assembly and
gears for damage and replace if
necessary, page 30
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