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Troubleshooting
Troubleshooting
Problem
Motor operates, but
displacement pump does not
operate
Displacement pump operates,
but output is low on upstroke
Displacement pump operates,
but output is low on down stroke
and/or on both strokes
Paint leaks and runs over side of
wet cup
Excessive leakage around
hydraulic motor piston rod wiper
20
Cause
Hydraulic pump valve is OFF
Pressure setting too low
Displacement pump outlet filter
(if used) is dirty or clogged
Tip or tip filter (if used) is
clogged
Hydraulic fluid too low
Belt worn or broken or off
Hydraulic pump worn or
damaged
Dried paint seized paint pump
rod
Hydraulic motor not shifting
Piston ball check not seating
properly
Piston packings worn or
damaged
Piston packings worn or
damaged
Intake valve ball check not
seating properly
Suction tube air leak
Hydraulic oil filter is dirty
Loose wet cup
Throat packings worn or
damaged
Piston rod seal worn or
damaged
Solution
Set hydraulic pump valve ON
Increase pressure, page 13
Clean the filter
Remove tip and/or filter and
clean
Shut off sprayer. Add fluid*. See
page 10
Replace belt
Bring sprayer to Graco
distributor for repair
Service pump. See Pump, page
41
Set pump valve OFF. Turn
pressure down. Turn engine
OFF. Pry rod up or down until
hydraulic motor shifts.
Service piston ball check. See
Pump, page 41
Replace packings. See Pump,
page 41
Tighten packing nut or replace
packings. See Pump, page 41
Service intake valve ball check.
See Pump, page 41
Replace filter.
Tighten wet cup enough to stop
leakage
Replace packings. See Pump,
page 41
Replace these parts. See
Pump, page 41
3A4401A
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