Fuel Pressure........I'm so confused.....

[Jonz]

I know this has been hashed out before and I just read 20 or so posts but Im still a little confused.



8 psi at idle is

4-5 psi while running

0 psi WOT



Pressure is being pulled from the side of the injection pump going into a mechanical autometer guage. I have also installed larger banjo bolts.



I read alot of posts that says they have higher psi but not that the lower readings are "Bad" Is this the case?



The truck runs great and I have seen no power loss anywhere. Even when the guage says 0psi and I have more throttle left she still pulls like mad.



If in fact these numbers are bad... . should I just replace the lift pump or do I need to add and additional pump to push as well?



Thanks for your patience and advice



Troy

 

[Pit Bull]

Your suppose to have minimum 10psi at idle and 8 at wot. Mine ran fine with a dead lift pump It's been 3K miles since I installed the new lift pump. It's putting out 14psi at idle and 10psi at wot. Still runs the same as when the lift pump was dead. Go figure????

 

[Sky]

Originally posted by Pit Bull

Your suppose to have minimum 10psi at idle and 8 at wot. Mine ran fine with a dead lift pump It's been 3K miles since I installed the new lift pump. It's putting out 14psi at idle and 10psi at wot. Still runs the same as when the lift pump was dead. Go figure????

It wouldnt run long with it dead. Mine was dead for who know how long and my truck one day just decided to die and that was that. You will notice when its starting to go your truck will lose power and stuff when its starting to happen. I would get it changed its harder on the fuel pump. I got mine replaced under the 100k warranty.

 

[speedracer]

Unless you have an understanding dealer, with your mods, warranty will be voided. If that's the case I would go to cummins and get one(typically about $150) and install it yourself. I believe having proper fuel pressure will prolong the life of the injection pump. If perchance you have a understanding dealer, have them do it. But, I would change the lift pump.

 

[andrewkoperdak]

I ditto speedracer. Have it changed. I had mine changed by the dealer. When I had less than half a tank of fuel I could only get 3 psi at idle after lift pump warmed up. Cold it worked really well. After 20 minutes of driving it would dive. Running you truck with a low out of spec lift pmp would be like running you engine with low oil pressure. Your injection pump get cooling and lube from the return fuel, reduce the flow and you increase heat and friction. I caught my problem before 20,000 miles and the repair is documented with DC so if my injection pump goes south on me they have a record of why it might have.

 

[Joel Richards]

When I had my '98 24v, the lift pump was almost dead for a [dealer] extimated 10k miles. As luck would have it, in the middle of B. F. Nowhere the truck just up-n-quit! It really sucked becasue I was towing a trailer at the time, on vacation :{. If I had known that it was bad, I would have replaced it. Do yourself a favor - get it replaced ASAP. Either by the dealer, or even better, do it yourself and learn more about your truck in the process.



Good luck.

Joel

 

[Chipstien]

It is bad.

Get it change quick.

 

[Steve Campbell]

I would suggest...

if you are going to change it yourself, mount it back by the tank. It will take more time this time around, but wil prolong its life and be a piece of cake to change in the future if necessary. I am using a 4601HP from Summitt at $80 back by the tank and have plenty of fuel.