Cummins ISC Fuel Problem

[Yankeebelle]

Hi all

Just had the fuel lift pump replaced on our coach which has the Cummins ISC 350 HP on it. When got it back from the shop drove it about 5 miles down the road and all good when it sputtered and died. After sitting on the side of the road looked and no fuel in the filter. Went through turning the key on and off to prime and a bit later fired back up. Drove down the road cautiously a few miles and pulled into the Pilot to add some fuel.

Went back on a backroad and ran it up to normal cruising speeds for about 10 miles and dawned on me probably had some air in it where they had the lines off, and maybe it finally purged out. Ran fine after that. Had it out a few times over the last two weeks running it and was great. Was out with it Monday and ran down the road about 2 hrs and start/stopped a few times. No problem. Yesterday cranked up fine - idled for 5 mins or so, went 100 yards and died. Went and bled the fuel filter and not much fuel in it. Muttered a few choice words. Could hear the pump cycling. Gave it a while and figured try to prime the filter again, and after a bit fired back up. Just parked back in the yard. Trying to figure out what could be causing that. Ran perfect for a couple weeks. No apparent leaks that can be seen.

Any thoughts would be appreciated.

Thanks
Bruce

[paul65k]

Wow........sorry I don't have an easy fix but I would look at the fuel lines between tank and filter and to the lift pump. On the surface, it sounds like it may be a fuel line, either fitting at tank, filter assembly or the line itself based on the way I understand your explanation.

I think if it was a lift pump or even an engine fuel pump the filter would be full and not empty when the problem crops up.

If there is any way to test the fuel line from the tank, if it was me, I would start there

[MountainMike]

Where I use to work we had a saying " for every action there is a reaction". They replaced the lift pump look at the fitting for the lift pump, my 04 has oring fitting connecting to the pump I would think that one of the orings has a cut or the flare connection is not tight. I am going to bypass the lift pump and install a Fass pump and filter system on engine in the next couple weeks. I believe this is a better system than the original lift pump.

[Alpine36]

Is the engine setting any trouble codes? Was stalling the reason they replaced the lift pump?
Sounds like you may have a fuel restriction or a vacuum (air) leak in the fuel line somewhere. Did they change the fuel filter when they changed out the lift pump? It may be a good idea to replace the fuel filter and cut the old one open to look for signs of fuel line deteriorating, I.E. black rubber. But agree with MM, check the fittings at the lift pump first.

[Arkansas RV]

Originally Posted by MountainMike

Where I use to work we had a saying " for every action there is a reaction". They replaced the lift pump look at the fitting for the lift pump, my 04 has oring fitting connecting to the pump I would think that one of the orings has a cut or the flare connection is not tight. I am going to bypass the lift pump and install a Fass pump and filter system on engine in the next couple weeks. I believe this is a better system than the original lift pump.

Mike, if you haven’t purchased your Fass pump yet, you might check out the industrial AirDog pumps, a more HD pump with a lot of advantages over the Fass. Check it out in the Cummins engine section.
Richard