Engine/Transmission (1998.5 - 2002) Lift Pump Pressures

[klaybus]

OK... . The drama continues with FP pressures. This morning in about 30 degree weather I went to start my truck (Not plugged in) & she fired right up as usual..... I looked at the FP gauge & it read 11 PSI & then dropped to 0 PSI. Stayed there for about 1 minute & then rose to 5 PSI. After about 5 minutes it climbed to 11 PSI.

Drove 330 miles today & @ idle I saw on average:



11 PSI @ idle

9-10 PSI cruising @ 70 mph

5 PSI +- @ WOT.....



All day @ idle it seemed OK, but this morning it was like it was dying.....



What do you guys think?



Clay





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[jmeehan]

Fuel pressure will rise and fall as the grid heater cycles. It sounds like this morning was a little colder then usual.

My pressure is about 14 at idle and 7 at WOT, but I get the same as you at cruise.

Could be the pump is getting tired and the heavier, colder fuel works it harder.

 

[Fireman Dave]

I'd say you're low - probably just a matter of time. Mine was very similar to yours. Now I have 0 more than not, but sometimes it's up to 12. They die like that sometimes, I'm told. It can be intermittent until it just pukes. Mine has been all over the place in the past 2 weeks. It's going in on Tuesday. I'm keeping my fingers crossed that it won't be up to 12 that day.

 

[Gary - K7GLD]

CJ's right - at first start on cold mornings, the grid heaters place a HEAVY load on the electrical system, look at your dash voltmeter while that is happening, and you will likely see HUGE rise-and-fall taking place in system voltage as your grid heaters cycle - I see a noticeable rise-and-fall on my fuel pressure too on cold mornings - even with an added pusher pump... Your overall pressures seem a bit low, but normal guage variations might account for that - is that what they have always been, or do they seem to be lower than you saw previously?

 

[Ncostello]

I'm using the latest greatest OEM lift pump available. Its only been on there since August. My idle is usually around 14. 5 to 15. And after several good WOT pulls up hills, I cant make it drop below 11psi. But the grid heaters will pull it down to 9 or 10 because of the tremendous electrical drain they put on the batteries. My pressure guage will go from 15 down to 10 in an instant then right back to 15psi when the grids go off... but thats OK cause its electrical supply is being stolen by the heaters for a moment.



But if yours is being pulled down to 0 then only back to 5 psi from the grid heaters, I'd say its got one foot in the grave and the other on a bar of soap .

 

[klaybus]

Great News! Got truck today from dealer & pressure is great! 15+- @ idle, cruising @ 13 PSI & WOT @ 11 PSI... . Dwayne Lane of Everett, WA was great how they handled it. Listened, Fixed & on time... . Great Job & covered under Cummins Warranty!