Troubleshooting
8 308870G
Engine operates, but displacement
pump does not operate (continued)
Electrical power is not energizing
clutch field
Check wiring connections. Page 15.
Reference control board diagnos-
tics. Page 21.
With pressure control switch ON
and pressure turned to MAXIMUM,
use a test light to check for power
between clutch terminals on control
board.
Remove black clutch wires from
control board and measure resis-
tance across wires. At 70_ F, the
resistance must be between 1.7
+0.2W; if not, replace clutch coil
241121.
Have pressure control checked by
authorized Graco dealer.
Clutch is worn or damaged Replace clutch. Page 13.
Pinion assembly is worn or dam-
aged
Repair or replace pinion assembly.
Page 13.
Pump output is low Strainer (31) is clogged Clean strainer
Piston ball (25) is not seating Service piston ball. Manual 308798.
Piston packings are worn or dam-
aged
Replace packings. Manual 308798.
O-ring (227) in displacement pump
is worn or damaged
Replace o-ring. Manual 308798.
Intake valve ball is not seating prop-
erly
Clean intake valve. manual 308798.
Engine speed is too low Increase throttle setting. Manual
308867.
Clutch is worn or damaged Replace clutch. Page 13.
Pressure setting is too low Increase pressure. Manual 308867.
Fluid filter (318), tip filter or tip is
clogged or dirty
Clean filter. Manual 308867 or
309091.
Large pressure drop in hose with
heavy materials
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 opti-
mum performance (50 ft minimum).
Problem Cause Solution
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