Cummins Fuel Problem????

muddin38yota

muddin38yota

Well-Known Member
Joined
Apr 13, 2005
Location
Concord
I've got an 01 cummins with...a Comp Hot Box, Jammer nozzles, and a Fass system.
The problem is that when I'm going down the interstate and give it throttle it will start jerking??????
My fuel gauge is showing bout 12psi, and I know that it should be running like 15psi.
What could be my problem?
The only thing I can think of that I have not done yet is....when my buddy installed my Fass system for me he did not remove the stock lift pump from the tank, and replace it w/ a downtube because he did not have one at the time.
Soooo is it straining so hard to pull the fuel through the stock lift pump that it is not creating enough fuel pressure?

Anybodys insight on this would be helpful
 
Unless you had a dealer update with the pump moved to the inside of the tank your factory lift pump should be on the side of the engine block. You did remove the factory filter when the FASS was installed right? Also is it time to change the filter on the FASS system? You might also make sure your box is not cutting on and off for some reason like a bad ground or maybe even look into a new map sensor cause if it is acting fruity it will be amped up by your box and the injectors. Does it do it with box off? Start there if the filters are clean, then you can eliminate factory stuff and move on the aftermarket things.
 
I wouldnt think he would have that good of pressure to start with if he had a intank pump in there since but would be one thing to check and def check the filters or connections to see if it is sucking air from somewhere.
 
Does the preasure sstay at 12 when it starts surging? Where is your gauge reading the preasure from?
 
When my old 1998 1/2 CTD with FASS and Edge Comp did the same thing it was a bad ground on the Comp Box....very aggravating until I found it! As for fuel pressure, you should be able to run down below 10 PSI before you start losing any power. My old stock lift pump mounted to the side of the block ran down to 6psi before I noticed any power loss and replaced it so 12psi is not too bad.

HTH

Sean
 
Most likely cause is a bad ground on the comp. Never ground any box to the battery, It's best to ground at the intake horn!

You will still have some interference with the grid heaters in that area, but you should be fine!

APPS Sensor can be reset , You should also check the voltage on it! I would also look into a VP-44 , Most can be had around 1050.00! Check for codes as well! If you continue to have problems drop me a PM and I'll go over the process of adjusting it!

Try and reset the apps first,

This procedure has shown to help 24 valve ISB engines. It is basically teaching the fly by wire accelerator on these trucks to reread the position of the pedal and it's limits. Most complaints this will help with is poor acceleration, improper shifting, bucking in 5 and 6 speeds. Has been known to increase fuel mileage in some instances.

One more thing, Most likely your fuel pressure is fine, As long as you dont see a drop at WOT! I'd say that you could have one of the low pressure springs that FASS used on a handful of pumps! I keep drawstraws (pickup tube) in stock and can have the pressure springs here in 2 days!

hope this helps!

1. Set parking brake
2. Disconnect negative battery cables on both batteries
3. Turn ignition key to run(to drain any remaining capacitors)
4. Let truck sit for 30 minutes( this is the recommended minimum)
5. Return ignition to OFF position
6. Reconnect both batteries and secure, not a timed event
7. Turn key to run position(not start) and depress accelerator pedal slowly all the way to the floor
8. Allow pedal to return to top position slowly
9. Turn ignition switch OFF
10.Release parking brake
 
Thanks for the suggestions, let me try em and I'll post back!!
 
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