Graco 3400 Repair Manual page 7

Problem
Pump output is low
Excessive paint leakage into throat
packing nut
Fluid is spitting from gun
Pump is difficult to prime
Clutch squeaks each time clutch
engages
High engine speed at no load
310813 Rev C
Cause
Strainer (16) is clogged
Piston ball (206) is not seating
Piston packings are worn or damaged
O-ring (227) in pump is worn or damaged Replace o-ring. Manual 309250.
Intake valve ball is not seating properly Clean intake valve. Manual 309250.
Intake valve ball is packed with material Clean intake valve. Manual 309250.
Engine speed is too low
Clutch is worn or damaged
Pressure setting is too low
Fluid filter (29), tip filter or tip is
clogged or dirty
Large pressure drop in hose with
heavy materials
Throat packing nut is loose
Throat packings are worn or damaged
Displacement rod is worn or damaged
Air in pump or hose
Tip is partially clogged
Fluid supply is low or empty
Air in pump or hose
Intake valve is leaking
Pump packings are worn
Paint is too thick
Engine speed is too high
Clutch surfaces are not matched to each
other when new and may cause noise
Misadjusted throttle setting
Worn engine governor
Solution
Clean strainer.
Service piston ball. Manual 309250.
Replace packings. Manual 309250.
Increase throttle setting. Manual 310802.
Adjust or replace clutch. Page 9.
Increase pressure. Manual 310802.
Clean filter. Manual 310802 or 309639.
Use larger diameter hose and/or
reduce overall length of hose. Use of
more than 100 ft of 1/4 in. hose signifi-
cantly reduces performance of sprayer.
Use 3/8 in. hose for optimum perfor-
mance (50 ft minimum).
Remove throat packing nut spacer.
Tighten throat packing nut just enough
to stop leakage.
Replace packings. Manual 309250.
Replace rod. Manual 309250.
Check and tighten all fluid connections.
Prime pump. Manual 310802.
Clear tip. Manual 309639.
Refill fluid supply. Prime pump. Manual
310802. Check fluid supply often to
prevent running pump dry.
Check and tighten all fluid connections.
Reduce engine speed and cycle pump
as slowly as possible during priming.
Clean intake valve. Be sure ball seat is
not nicked or worn and that ball seats
well. Reassemble valve.
Replace pump packings. Manual 309250.
Thin the paint according to the sup-
plier's recommendations
Decrease throttle setting before prim-
ing pump. Manual 310802.
Clutch surfaces need to wear into each
other. Noise will dissipate after a day of
run time.
Reset throttle to 3300 engine rpm at no
load
Replace or service engine governor
Troubleshooting
7