Hitachi 308996J - Manual (Page 11)

308996 11
Troubleshooting Chart
WARNING
To reduce the risk of serious injury whenever you
are instructed to relieve pressure, always follow the
Pressure Relief Procedure on page 8.
1. Relieve the pressure.
2. Check all possible causes and problems before
disassembling the pump.
PROBLEM CAUSE SOLUTION
The pump fails to oper-
ate. Restricted air line or an inadequate air
supply; closed or clogged valves. Clear the line; increase the air supply.
Check that the valves are open.
Obstructed fluid hose or gun;
the fluid hose ID is too small. Open, clear*; use a hose with a larger ID.
Fluid has dried on the displacement rod. Clean the rod; always stop the pump at the bottom
of its stroke;
keep the wet-cup 1/3 filled with a compatible sol-
vent.
Dirty, worn, or damaged motor parts. Clean or repair; see the separate motor manual
308995.
The pump operates,
but the output is low on
both strokes. Restricted air line or an inadequate air
supply; closed or clogged valves. Clear the line; increase the air supply.
Check that the valves are open.
Obstructed fluid hose or gun;
the fluid hose ID is too small. Open, clear*; use a hose with a larger ID.
Worn u–cup seals in the displacement
pump. Replace the u–cup seals.
The pump operates,
but the output is low on
the downstroke. Held open or worn intake valve. Clear the valve; service.
The pump operates,
but the output is low on
the upstroke. Held open or worn piston valve or u–cup
seals. Clear the valve; replace the u–cup seals.
Erratic or accelerated
pump speed. Exhausted fluid supply. Refill the supply and prime the pump.
Held open or worn piston valve or u–cup
seals. Clear the valve; replace the u–cup seals.
Held open or worn intake valve. Clear the valve; service.
* To determine if the fluid hose or gun is obstructed, follow the Pressure Relief Procedure on page 8. Discon-
nect the fluid hose and place a container at the pump fluid outlet to catch any fluid. Turn on the air just enough
to start the pump. If the pump starts when the air is turned on, the obstruction is in the fluid hose or gun.
NOTE: If you experience air motor icing, call your Graco distributor.