Engine/Transmission (1994 - 1998) LP pressure low overflow valve ok

[Jschafer]

I am 90% sure my LP is about done (345k it has been a good run). The primer button on the pump never worked so years ago I put a elect pump in the line at the tank just a small 7 psi one (this is nice).

A month ago truck started running poor so I changed the fuel filter and then turned on the key to prime the filter and nothing so checked out my elect pump and it was dead, so i replaced it and everything was ok.



The other day i checked my fuel pressure and found it to be low 18 at idle and 28 at 2000 so I checked overflow valve and found it to be a touch over 1/2" so I streched a touch to see if it would help and the reading came up to 20 and 30 still lower than should be remembering I have 7psi pre pressure I am sure the LP is about done.



I have read that you change the o-rings but will this help pressure or just a leak repair?



Where is the best placeto purchase new Lp Is there a hose issue with the new pumps being in the wrong place.



Thanks

Joe

 

[Joe G.]

The electric pump may be a restriction. The mechanical lift pump on your truck should not need any help. It sounds like you have a small air leak. The O-rings are only to repair a leak. There is no way to put your lift pump in the wrong place. It's mechanical and cam driven. Anything you read that applies to 24 valve engine fuel system does NOT apply to 12 valve engines. In spite of the electric pump, your mechanical lift pump is still within specs, about 18 at idle and 25 at highway speeds. The hose problem is because of air leaks not placement. The primer button takes a LOT of pushes to fill the fuel filter so it may be ok. If you would like a write up about how the fuel system works on a 12 valve and how to fix it e-mail me a -- email address removed --

 

[Jschafer]

Thanks Joe

The elect pump has been on the truck for over 300k. The pressures were ok back then.

I read while doing a search that the new pumps have one of the hose connections in a differant spot by about 1".



Where is the best place to pick a new lift Pump

 

[bmoeller]

I bought my lift pump from the Case IH dealer. less than $100, including the 2 gaskets. Just have to swap a fitting between the 2 pumps. It is obvious which one it is when have them side by side.



https://www.turbodieselregister.com/forums/showthread.php?t=97766



Lift Pump: J936317

Gasket: J939258 (two required)