Engine/Transmission (1998.5 - 2002) Lift Pump Dies at Night

[Slim's Ram]

I have searched the lift pump threads and can't seem to find the answer to my problem. The lift pump on my 98. 5 holds 15 psi at idle and 10 psi when accelerating during daytime all day long. The problem is at night only it will lose pressure slowly and by the time you go 35 miles or so the fp guage will be down to 0 psi.

The lift pump has only been on for 12,000 miles or so.

My fp guage which was just recently installed 500 miles ago is a Diprocal Mechanical.

Is my guage faulty or is it time for yet another call to Cummins.



Thanks for the endless information on this site.



Chris

 

[JKinney]

What happens if when driving at night if you pull over and turn your lights off does your preasure come back?

 

[Slim's Ram]

No pressure stays put. Went out this morning cranked truck to let warm up.

Went back out 5 mins later fuel pressure had went from 15 psi to 4 psi just idling.

I think I will just order a new lift pump and a relocation kit to go with it.

Any other suggestions.



Thanks Again

Chris

 

[JKinney]

Check ebay for new pumps

 

[RAJohnson]

Do you have a isolator in the gauge line?? You have air in there I would bet or not enough antifreeze if you have the isolator.