Graco LineLazer II 3900 Instructions Manual page 7

PROBLEM
Pump output is low on p p
upstroke. upstroke
Pump output is low on down- p p
stroke or on both strokes. stroke or on both strokes
Paint leaks into wetcup. p
Fluid delivery is low. y
Fluid is spitting from gun.
Pump is difficult to prime.
Clutch squeaks each time
clutch engages.
High engine speed at no
load.
CAUSE
Hose inlet screen (27) is clogged.
Piston ball (25) is not seating.
Piston packings are worn or damaged.
O-ring (17) in displacement pump is worn or
damaged.
Hose strainer (27) is clogged.
Piston packings are worn or damaged.
Intake valve ball is not seating properly.
Engine speed is too low.
Clutch is worn or damaged.
Wetcup is loose.
Throat packings are worn or damaged.
Displacement rod is worn or damaged.
Inlet screen is clogged.
Pressure setting is too low.
Engine speed is too low.
Fluid filter (318), tip filter or tip is clogged or
dirty.
Large pressure drop in hose with heavy
materials.
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.
Small irregularities of new clutch surfaces
grind together and cause noise
Misadjusted throttle setting.
Worn engine governor.
SOLUTION
Clean inlet screen.
Service piston ball. See manual 308798.
Replace packings. See manual 308798.
Replace o-ring. See manual 308798.
Clean strainer screen.
Replace packings. See manual 308798.
Clean intake valve. See manual 308798.
Increase throttle setting. See manual 308873.
Replace clutch. See page 10.
Tighten wetcup just enough to stop leakage.
Replace packings. See manual 308798.
Replace rod. See manual 308798.
Clean inlet screen.
Increase pressure. See manual 308873.
Increase throttle setting. See manual 308873.
Clean filter. See manual 308873. Or, see gun
instruction 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 perfor-
mance (50 ft minimum).
Check and tighten all fluid connections.
Reprime pump. See manual 308873.
Clear tip. See gun instruction manual.
Refill fluid supply. Prime pump. See manual
308873. 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. Reas-
semble valve.
Replace pump packings. See manual 308798.
Thin the paint according to the supplier's
recommendations.
Decrease throttle setting before priming pump.
See manual 308873.
Clutch surfaces need to wear into each other.
Noise will dissipate after a day of run time.
Reset throttle to 3600–3800 engine rpm at no
load.
Replace or service engine governor.
308874 7