Engine/Transmission (1998.5 - 2002) Can't Figure Out My FP Problem!!! Help

[trqmnstr]

I've had my truck for 2 years with no problems with stock fuel system. I was reading 15 idle and 11 WOT. About 4 months ago, my FP gauge started dropping to 12 and 9. No problem, I'll just change lift pump, right? I changed to a brand new lift pump and filter. It made no difference. I then figured I had a clog in my tank pickup filters. My float bad bad anyway so I dropped the tank and replaced the entire $350 pickup unit. No change. OK, so I got a bad lift pump. I got it warrantied and still no change. I just killed my VP and I need to fix the pressure problem ASAP. I'm now idling at 8 psi and I'm not going to drive it until I fix it. Please provide some suggestions.

 

[CTHunter]

What do you mean by saying you killed your VP and now idling at 8psi? you put in a new VP to get the truck running again? I too just replaced an eratic lp and the new one is just like you described, 12 and 9psi. I think that someone said the newest lp's are equiped with a bypass and somehow flow more but with less pressure, which I don't understand completely, maybe some one else will chime in that knows more. If you killed your VP with this newer lp I think I'll quit driving my truck until I get my pressure back to 15psi.

 

[DavidC]

You might check here to see ideas or if it matches your problem.

http://turbodieselregister.com/forums/showthread.php?t=162110



Dave

 

[PRout]

Are you sure the gauge is working correctly?

 

[WestTN]

I have the new pump with built in bypass and I get 14. 5 idling with 12 cruising. I was going to suggest you might have slime growing in your tank, but the fuel pickup change would have made that one obvious.

Unless something else is changed when the pump is changed that would reduce overall restriction in the system, less pressure will always mean less flow. That is a simple law of physics.

 

[RRFinch]

Well, no one has yet suggested low voltage to the LP, so I guess I will.

Check the wiring to the LP. If it is partially abraded, you will not get full current to the LP and it will run slower... . giving lower pressure.

 

[Jed]

you need to check you gauge with a test gauge my pressure was always 14 to 16 and then one day I had 10 then 5 then 7 I drove Dan at FASS nuts because i have also lost a vp. Short story test gauge showed 19lbs... ... bad isolator//!!

 

[SMolteberg]

I agree with Jed, had same trouble with low FP readings but doublechecked it with a testgauge and my Di-procol where way off. Turned out that air had sneaked into the antifreeze after the isolator after a years use, bled out the air and everything where good. But I spendt two weeks of troubleshooting and changing a perfectly good LP.

 

[CCahill]

Take Brett's advise... you'll be $ ahead in the long run... .

 

[Mark Craig]

trqmnstr,



1st thing is check the gauge for air in the lines, it happens more than you might guess! Then get a test gauge to verify the true pressue, tape it to the windshiled as you drive so you can see it under load. If they both show low pressure just bail on the stock lift pumps, they are the cause of more VP44's failures than should have ever been allowed by Dodge!! The info I have lately shows the newer intank pumps reliability is much better but it's PSI and such is as bad if not worse than the old style. I have a couple of local customers that won't install one of our VP44's unless the customer at least adds the FASS HPFP pump only system (they really wan thtem to add the full FASS system) as they are so concerned about warranty come backs with the old style lift pump or the newer in tank lift pump.



If you want to fix it forever get the FASS system, plus you lose entrapped air and get a MUCH better filtering system too!!



Mark @ DPPI