I have a Hyundai 140 LC-7 excavator that has become hard to start. After excessive cranking, it eventually starts and runs strong like it should. It has the Zexel fuel feed primer and I loosened the plunger, pumped it several times, tighten the plunger, and it starts. But it continues to loose prime. I also put a check valve in the fuel supply line. Do those Zexel plungers need to be replaced often or do I need to look for another remedy?
Fuel lines need replacing?
Those little lift pumps can be rebuilt easily and there are kits for them. They do act as a fuel line check valve but as mentioned also check rubber fuel lines for integrity. If after an overnight setting the engine has to crank an extended time before firing off, the lift pump would be highly suspect; as would any fuel check that maintains fuel gallery pressure if present in/on the pump housing itself. If the engine fires easily then starves out, the rubber fuel lines prior to the pump or plumbing are suspect.
Thanks for the replies! The fuel lines seem ok, no deterioration, damage, or wet are areas seen. Once it’s started it runs strong. So does those plungers go bad, or do I need to try to replace/rebuild the lift pump? thanks!
The lift pump has "O" rings and sometimes little discs and springs that can go bad. Any injection pump shop will be able to set you up with a rebuild kit. Usually easy to do on a clean work bench but do ensure everything is clean while you are working and cap all open lines to preclude dirt entrance.
Take a pair of vice grips and clamp them on the return line. Not tight enough to stop flow, just enough to restrict a bit and see what happens. We have some air compressors running a similar fuel system. Between a worn lift pump and return check valve it would lose prime. That kept it happy until I could get the lift pump rebuilt and install a new check valve. I tinkered with the lift pump, didn’t see anythung obvious. Ended up having the diesel shop rebuild it, they often have to lap a couple surfaces to get it right.
90% of the time, new seats have to be cut in the supply pump.. But if u wanna take a shot at it, the kit for a 2 valve supply pump is: DGK 301..& if u wanna new hand primer its dgk301-h
Thanks Pumpguy, I was hoping you would reply. Please excuse my ignorance, but what does it involve to cut new seats in the supply pump?
Special tool..