Graco GMAX 3400 Operation page 29

Problem
Engine operates, but displacement
pump does not operate
Pump output is low
3A6400A
Cause
Error code displayed.
Pump switch is OFF.
Pressure setting too low.
Fluid filter is dirty.
Tip or tip filter is clogged.
Displacement pump piston rod is stuck
due to dried paint.
Connecting rod is worn or damaged.
Drive housing is worn or damaged.
Electrical power is not energizing
clutch field.
Clutch is worn, damaged, or incorrectly
positioned.
Pinion assembly is worn or damaged.
Strainer is clogged.
Piston ball is not seating.
Piston packings are worn or damaged.
O-ring in pump is worn or damaged.
Intake valve ball is not seating
properly.
Intake valve ball is packed with
material.
Engine speed is too low.
Clutch is worn or damaged.
Pressure setting is too low.
Fluid filter, tip filter or tip is clogged or
dirty.
Large pressure drop in hose with
heavy materials.
Solution
See LED Display Messages, page 38.
Turn pump switch ON.
Turn pressure adjusting knob clockwise to
increase pressure.
Clean filter.
Clean tip or tip filter (see gun manual).
Repair pump (see pump manual).
See Parts manual.
See Parts manual.
See Parts manual.
See LED Display Messages, page 38.
With pump switch ON and pressure turned to
MAXIMUM, use a test light to check for power
between clutch test points on control board.
Remove clutch wires from control board and
measure resistance across clutch coil. At 70°
F, the resistance must be between for 3900 -
1.2 + 0.2 Ω, for 5900/7900 1.7 ± 0.2 Ω; if not,
replace pinion housing.
Have pressure control checked by authorized
Graco dealer.
Adjust or replace clutch. See page 39.
Repair or replace pinion assembly. Page 39.
Clean strainer.
Service piston ball (see pump manual).
Replace packings (see pump manual).
Replace o-ring (see pump manual).
Clean intake valve (see pump manual).
Clean intake valve (see pump manual).
Increase throttle setting (see operation
manual).
Adjust or replace clutch. Page 39.
Increase pressure (see operation manual).
Clean filter (see gun manual).
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
optimum performance (50 ft minimum).
Troubleshooting
29