Hitachi 3900 important safety instructions Clean filter. Manual 310892 or

		Troubleshooting
Problem	Cause	Solution
Pump output is low	Strainer (82) is clogged	Clean strainer.
	Piston ball is not seating	Service piston ball. Manual 310894.
	Piston packings are worn or damaged	Replace packings. Manual 310894.
	O-ring in pump is worn or damaged	Replace o-ring. Manual 310894.
	Intake valve ball is not seating properly	Clean intake valve. Manual 310894.
	Intake valve ball is packed with material	Clean intake valve. Manual 310894.
	Engine speed is too low	Increase throttle setting. Manual 310892.
	Clutch is worn or damaged	Adjust or replace clutch. Page 10.
	Pressure setting is too low	Increase pressure. Manual 310892.
	Fluid filter (56), tip filter or tip is clogged or	Clean filter. Manual 310892 or 309639.
	dirty
	Large pressure drop in hose with heavy	Use larger diameter hose and/or reduce
	materials	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).
Excessive paint leakage into throat	Throat packing nut is loose	Remove throat packing nut spacer. Tighten
packing nut		throat packing nut just enough to stop leak-
		age.
	Throat packings are worn or damaged	Replace packings. Manual 310894.
	Displacement rod is worn or damaged	Replace rod. Manual 310894.
Fluid is spitting from gun	Air in pump or hose	Check and tighten all fluid connections. Rep-
		rime pump. Manual 310892.
	Tip is partially clogged	Clear tip. Manual 309639.
	Fluid supply is low or empty	Refill fluid supply. Prime pump. Manual
		310892. Check fluid supply often to prevent
		running pump dry.
Pump is difficult to prime	Air in pump or hose	Check and tighten all fluid connections.
		Reduce engine speed and cycle pump as
		slowly as possible during priming.
	Intake valve is leaking	Clean intake valve. Be sure ball seat is not
		nicked or worn and that ball seats well.
		Reassemble valve.
	Pump packings are worn	Replace pump packings. Manual 310894.
	Paint is too thick	Thin the paint according to the supplier's
		recommendations
	Engine speed is too high	Decrease throttle setting before priming
		pump. Manual 310892.
Clutch squeaks each time clutch	Clutch surfaces are not matched to each other	Clutch surfaces need to wear into each
engages	when new and may cause noise	other. Noise will dissipate after a day of run
		time.
High engine speed at no load	Misadjusted throttle setting	Reset throttle to 3300 engine rpm at no
		load.
	Worn engine governor	Replace or service engine governor
Gallon counter not working	Bad sensor, broken or disconnected wire.	Check connections. Replace sensor or
	Displaced or missing magnet.	wire. Reposition or replace magnet.
No display, sprayer operates	Display damaged or has bad connection	Check connections. Replace display.

310893L 7