Fuel Lift Pump Replacement

[jimemeone]

98' HRE 5'9 Cummins ISB
Problem starting where upon start would run for a couple seconds and then die, would have to crank for 10/15 seconds before it would catch again while playing with the gas pedal. Local former military truck mechanic in the RV park tested and said the lift pump needs to be replaced, no charge for his time, and said the pump could be external or in the tank, so how do I determine location and if external can it be a DIY fix ?
Thanks in advance for all replies,
Jim & Diane 37' HRE

[ret60sp]

Originally Posted by jimemeone

98' HRE 5'9 Cummins ISB
Problem starting where upon start would run for a couple seconds and then die, would have to crank for 10/15 seconds before it would catch again while playing with the gas pedal. Local former military truck mechanic in the RV park tested and said the lift pump needs to be replaced, no charge for his time, and said the pump could be external or in the tank, so how do I determine location and if external can it be a DIY fix ?
Thanks in advance for all replies,
Jim & Diane 37' HRE

Jim,

I know exactly what your problem is. The first thing you need to do is to see if there is a small cartridge inline fuel filter hidden up above your rear axle. It is NOT the primary filter. Some of the older units had this hidden filter inline and its causes many vehicles to end up in the boneyard because no one could figure out why the engine won’t start or stay running. If and when you find it, remove it or bypass it and have the fuel go straight to the lift pump. It goes from the lift pump through the primary filter, to the injector pump. One simple way to prove that you have an inline filter clogged is to replace your lift pump and then start cycle your ignition switch (switch on, bump the starter, leave the switch on and the pump should run for 20 seconds) Place a 5 gallon bucket under your primary filter housing, open the water drain valve and perform the starter bump procedure. You should see a hard stream of fuel blasting out of the water drain for that 20 seconds, giving you about a quart of fuel in your catch basin. If the amount of fuel is not close to a quart, you have an inline obstruction. That inline obstruction is more than likely that awful inline filter that Cummins or the coach manufacturer placed in the system as a bad joke.
Yes, replace your lift pump. It’s a piece of junk from Cummins that is not designed to be pulling fuel from the distance that an RV has from the fuel tank, and with the advent of an obstruction like the inline rock filter, its almost a guarantee that it is not giving you sufficient fuel pressure (5-18 psi) on the pressure side, and this excess negative pressure (vacuum) condition on the suction side wears the OEM lift pump out very quickly. Replace it with another one for ($100-$135) if you want to be back under there in 3 years replacing it again, or replace it with a FASS DRP02 ($300) and call it fixed. Yes you could install a fancy FASS or AirDog that removed the air bubbles and makes dinner for you ($600), the choice is yours on that one. The more expensive pump can’t be mounted as a direct replacement, whereas the DRP02 is indeed a Direct Replacement Pump (DRP).



Hope this helps!


Don

[mike toon]

Don on your unit I see its a 2003, as mine is.
Did you install the FASS DRP02.
Mike

[ret60sp]

Originally Posted by mike toon

Don on your unit I see its a 2003, as mine is.
Did you install the FASS DRP02.
Mike

I did, but my chassis is a 2002 model and the coach build is a 2003 model - this seems to be a change point on certain parts.


The critical part is to make sure you have the 5.9l ISB in either 275, 300 or 330 hp. Mine is 300hp.

[winniman]

The 300 hp is different than the 275 the OP has. The 300 hp went to the high pressure fuel rail. The 275 hp from 1998 to 02 uses the vp44 injection pump. I would suggest to the OP not to drive it the way it is. If the lift pump is malfunctioning, the vp44 will be overtaxed trying to draw fuel from the tank. These lift pumps are famous for failing, and taking the vp44 will it. The vp44 can cost as much as 5 to 7000 dollars to replace. The lift pump is only several hundred. I replaced mine with the FASS pump system. Other than having to run a new return line back to the tank, it was relatively simple. Even replacing the original is better than letting it wreck the big pump. Unfortunately, it was too late for me, and my vp44 had to be replaced. I looked all over my frame for a hidden fuel filter. None was found, but that doesn't mean that maybe the OP doesn't have one of these unicorns that they installed them on. There is documentation of them being installed on some rvs, but no record of which ones they were put on. If you are getting low fuel pressure, get it fixed fast. A code reader should tell you if you are getting any codes of low fuel pressure. Good luck, and I hope it isn't too late for your vp44.

[jash1234]

[mike toon]

The little frame filter I ordered some time ago.Last month I got under the motor to replace it.It is above the rear axle.
Long story short that fricken think is hard to get at ,now that im in my sixties.I tried twice to get it and just couldn't get at it with both hands.
I took the motor-home to the local truck service center.The mechanic got under and replaced it in no time.When he was done he asked"would 20 dollars be alright".
I gave him the 20 and another 20 for his lunch.

[rikadoo]

Hey Mike, this is some REALLY great info, do you by chance have the part # of that filter? also was that a cummins part or ???