so i was driving home from work today, 30 min trip, no racing, nothing crazy. so i get home and let my truck cool down and look at the fuel psi, its fluctuating from 8 psi to 18 psi and going as low as 2 PSI!
so turn the truck off immediatly, thinking the holley quit working.
pop the hook check everything out, everything looked ok.
so i turn the key on and listen for the holley and its running like a charm.
i start it up and the same thing the fuel psi goes from about 8psi to 18psi and sometimes all the way to 2 psi!

whats wrong, both VP44 and LP were replaced about 6-7 months ago, i added the holley blue about a month after getting them replaced.
could my LP be bad and not letting full fuel to the VP, i m usually at 22-24 psi@ idle. could the VP44 be bad?

heres a crazy question some might not like, should i try and kill my vp if its the LP, so i can get both new since there under warranty?
if your wondering why, i plan on adding a box and would like the vp to be up to par.
please help

thanks in advance, dieselfan

 

Are you using an isolator on the fuel pressure gauge? Lots of fluctuation fuel pressure posts lately, myself included same symptoms but I'm using an isolator and haven't removed it yet. Could this be related to ULSD killing isolators? I know it's a long shot but I've read several posts on this exact topic.

Good luck and keep us posted.

 

all i have is a sending unit that is electronic (i think). could this be bad?
its only a month or so old.

thanks dieselfan

 

Could be. verify the pressure with a mechanical guage.

 

wheres the best place to get one.
i remember someone saying they used a a/c compression gauge.

thanks dieselfan

 

Beware of the gasket on the AC gauge if running BD, it eats it.

 

I am having the same problem with fuel pressure. Had a new LP about 5K ago and new VP44 about 1K ago. Everything fine with about 16psi at idle and 12psi cruising at 65mph then I started seeing pressure momentarily drop to 5psi. The last 50 miles it stayed at 5 psi at 65 mph. When I got home I shut it off and then bumped the starter and fuel pressure stayed at 16 psi for 20 seconds or so. I did this 3 times with same result. I have cleaned connection and checked voltage. I guess the LP is failing. I love this truck but I am losing confidence in its reliabilty. This fuel pump issue should not be that hard to solve. It astounds me that Dodge would rather pay for all these LP's and VP44's under warranty than come up with a solution, let alone all the customer dissatisfaction. I have friends and customers with these trucks and they have all had pump failures at some point. Now that my warranty has expired this issue is going to be much more than an inconvience. I dont know whether to rig up some other pump system or get rid of it.

 

i feel the same way. none of my stuff was under warranty.
i love my truck when its running trouble free,but ive had a few problems and everytime i think about selling it for nice 3rd gen 4x4.

dieselfan

 

Just a thought if you had recent work done on lp / ip. When my first lp was replaced by dealer I was have pressure fluctuations from 14 psi to 7 psi. I took it back several time complaining about it. They kept telling me nothing was wrong and everything was w/in specs. A week out from elk camp I decided to change the lp myself ( was going with a bunch of ford guys) When I changed the lp I found the rubber hose from the lp to the filter housing was kinked.
CJ

 

I have 108k miles on a 2002 and my 4th lift pump is going out. This one and number 3 did the same thing with the crazy pressure readings. It is like one of the vanes in the pump gets stuck open sometimes. I simply don't understand the fluctuating pressures. You would think the thing would just work or quit dead.

Number 3 was new when I moved it to the frame rail. It lasted about six months. Number 4 has lasted about six months. I bought numnber 3 from CarQuest and they have a limited lifetime warranty and replaced 3 with 4. I am about to take in number 4 to get number 5.

They seem to be going out faster after I moved the LP to the frame rail.

Any thoughts on that.

Bobby

 

i hope its my LP.
this morning i start it up and the same thing 18psi to 2psi @idle, then it settles at 18 psi so i take off and it goes up to like 20psi on the interstate and stays there. i get to work and it starts dropping but not too much, proably 14psi-16psi.
at lunch i call Quadzilla customer service and ask if they had any failures w/ the sending units. they said only 1 and it didnt work period, no flucatuating psi. they told me to check my connections, so i did and nothing was unhooked.
so i get in to drive home 18psi@ idle pretty steady, i drive home it holds like 20psi the whole way. so i figured its fixed, WRONG, i get home and let it idle to cool down and its 18psi @idle then 16, 14,etc.,etc., all the way to 2psi and back up and down again.
man i hope its just the LP.

heres a good question. if my LP dies will my holley be able to push fuel though the dead LP?


thanks dieselfan

 

Do you already have the Holly on there? If you do, and your fp is dropping, I'd have to say, no.

My second factory pump was dropping like that, only to "0" at times. I replaced it with a FASS HPFP and have been smiling ever since.

 

Wasn't that the reason behind the Cummins Campaign pump rollout; to allow the IP to draw fuel throught the stock LP if it failed? Pushing from behind is another matter. Not sure if that would work

 

Dieselfan did you find uot what going on? I got my oil changed yesterday and fuel filter,now my fuel gauge jumps around now.16 at idle then 13 driving drops down 2pis back up 14 back and forth.if i wot it stays at 8lb.

 

wildwood2500,
no, not yet. i plan on bring it in on monday, since i had my VP and LP done by a shop and its under warranty.

it seems like its the LP going bad from what other readers have said.

the thing that gets me is its fine cruising but when it starts idling for couple minutes thats when the psi really starts dropping and fluctuating bad!
also my filters are fresh and batteries are brand new.


still wondering, dieselfan