Troubleshooting Guide - Graco EM 390 Instructions And Parts List

Pressure Relief Procedure
To reduce the risk of serious bodily injury, including fluid
injection, splashing in the eyes or on the skin, or injury
from moving parts, always follow this procedure when
you shut off the sprayer, when checking, adjusting or
cleaning the system, and when changing spray tips.
1. Engage the gun safety latch.
2. Turn the ON/OFF switch to OFF.
3. Unplug the power supply cord.
Check everything in the chart before disassembling the sprayer.
PROBLEM
Electric motor won't run
Electric motor stops while
spraying
Electric motor runs, but low paint
output or no paint output;
or pump is not stroking
See the PROBLEM, "Not enough
paint pressure", on page 17, also
.

TROUBLESHOOTING GUIDE

WARNING
CAUSE
Power cord or extension cord un-
plugged, or damaged, or building circuit
breaker or fuse has tripped
1
Motor overload switch has opened
Pressure setting too low
2
Pressure control frozen or damaged by
3
over–pressurization
Power cord or extension cord un-
plugged, or damaged, or building circuit
or fuse is blown
1
Motor overload switch has opened
Pressure setting too low
Spray tip or filter plugged
Wrong type extension cord
Piston ball check not seating
Piston packings worn or damaged
Intake valve ball check not seating
Pump is frozen
Filter element installed upside down
2
Pressure control frozen or damaged by
3
over–pressurization
Drive assembly damaged
Displacement pump worn or damaged
Sprayer is not primed.
4. Disengage the gun safety latch. Hold a metal part
of the gun firmly to the side of a grounded metal
pail, and trigger the gun.
5. Engage the gun safety latch.
6. Open the fluid pressure drain valve and leave it
open until you start the sprayer again.
If you suspect the hose or spray tip is completely
clogged or that pressure is not fully relieved after fol -
lowing the steps above, VERY SLOWLY loosen the tip
guard retaining nut or hose end coupling and relieve
pressure gradually. Now loosen the part completely.
Clear the tip or hose obstruction.
SOLUTION
Check, reset or replace.
Unplug power supply cord, relieve pressure, al-
low motor to cool, clear motor air passages of
dirt and overspray, decrease pressure.
Increase pressure.
Try to thaw, or replace pressure control.
Check, reset or replace.
Unplug power supply cord, relieve pressure, al-
low motor to cool, clear motor air passages of
dirt and overspray, decrease pressure.
Increase pressure.
Remove and clean.
Use maximum 200 ft. (61 m), 3 wires, 12 gauge,
grounded extension cord.
Service the pump. See page 18.
Replace the piston. See page 18.
Service the pump. See page 18.
2
Thaw
Install element correctly. See page 14 or manual
307–273.
Try to thaw, or replace pressure control.
Replace drive housing. See page 21.
Replace displacement pump. See page 18.
Prime sprayer. See page 10.