Hitachi 1800 User Manual

1.

Relieve the pressure, page 12. 

2.

Check all possible causes and problems before dis-
assembling the pump.

To determine if the fluid hose or gun is obstructed, relieve the pressure, page 12. Disconnect the fluid hose and 
place a container at the pump fluid outlet to catch any fluid. Turn on the air/hydraulic power just enough to start the 
pump. If the pump starts, the obstruction is in the fluid hose or gun.

Pump fails to operate.

Restricted line or inadequate air/hydrau-
lic supply; closed or clogged valves.

Clear; increase air/hydraulic supply. 
Check that valves are open.

Obstructed fluid hose or gun/valve; fluid 
hose ID is too small.

Open, clear*; use hose with larger ID

Fluid dried on displacement rod.

Clean; always stop pump at bottom of 
stroke; keep wet-cup 1/3 filled with com-
patible solvent.

Dirty, worn, or damaged motor parts.

Clean or repair; see separate motor 
manual.

Pump operates, but output low on both 
strokes.

Restricted line or inadequate air/hydrau-
lic supply; closed or clogged valves.

Clear; increase air/hydraulic supply. 
Check that valves are open.

Obstructed fluid hose or gun/valve; fluid 
hose ID is too small.

Open, clear*; use hose with larger ID

Bleeder valve open.

Close.

Fluid too heavy for pump priming.

Use bleeder valve, page 13; use ram.

Worn packings in lower.

Replace packings.

Pump operates, but output low on down-
stroke.

Held open or worn intake valve.

Clear valve; service.

Fluid too heavy for pump priming.

Use bleeder valve, page 13; use ram.

Pump operates, but output low on 
upstroke.

Held open or worn piston valve or pack-
ings.

Clear valve; replace packings.

Erratic or accelerated pump speed.

Exhausted fluid supply.

Refill and prime.

Fluid too heavy for pump priming.

Use bleeder valve, page 13; use ram.

Held open or worn piston valve or pack-
ings.

Clear valve; replace packings.

Held open or worn intake valve.

Clear valve; service.