Troubleshooting - Graco 390 Repair Manual

Troubleshooting

WARNING
Read Electric Shock Warning, page 3, Burn Hazard
Warning, page 4 and Pressure Relief Procedure,
page 7.
Problem
Motor Won't Operate
Basic Fluid Pressure
Basic Mechanical
310824C
What To Check
(If check is OK, go to next check)
1. Pressure control knob setting.
Motor will not run if set at mini-
mum (fully counter-clockwise).
2. Spray tip or fluid filter may be
clogged.
1. Pump frozen or hardened paint
2. Displacement pump connecting
rod pin. Pin must be completely
pushed into connecting rod and
retaining spring must be firmly in
groove or pump pin.
3. Motor. Remove drive housing
assembly. See page 15, Drive
Housing Replacement. Try to
rotate fan by hand.
What To Do
(When check is not OK, refer to this column)
Slowly increase pressure setting to see if motor
starts.
Relieve pressure, page 7. Then clear clog or
clean gun filter. Refer to gun instruction manual,
309639.
Thaw sprayer if water or water-based paint has
frozen in sprayer. Place sprayer in warm area to
thaw. Do not start sprayer until thawed com-
pletely. If paint hardened (dried) in sprayer,
replace pump packings. See page 13, Dis-
placement Pump Replacement.
Push pin into place and secure with spring
retainer. See page 13, Displacement Pump
Replacement.
Replace motor if fan won't turn. See page 26,
Motor Replacement.
Troubleshooting
9