Revised Lift Pump

[Cliffman]

Has anyone had a revised lift pump go bad? If so, Maybe we should post the model # of the pump so we can track it. Supposedly Cummins has addressed this issue and corrected the problem with their updated pump. I have 20k on my revised pump and so far no drop in pressure.

 

[pwr2tow]

The lift pump has been revised three times that I know of and my first revised pump (#3938435) just went out a few miles ago at 38,000 miles. #'s 3938435, 3938467, 3990105.



original pump-----16,000 miles on truck # unknown

second pump-----24,000 miles on truck # unknown

Third pump--------38,000 miles on truck #3938435

fourth pump------1,000 on pump and still running#3990105



When I picked up my last lift pump at cummins they told me they were not aware of any problems. They also told me they have a 99 dodge truck as their shop truck with 130,000 miles on it and have never changed the lift pump. Leaves me puzzled???



Edit:: When pump would go out it would jump all over the gauge, some times go dead for awhile and then come back up, then it would stabilize and slowly decline over miles.



Ron

 

[Cliffman]

Good Info

That's the kind of info we’re looken for Ron. Was it a slow decline in pressure or did it just drop all at once?

 

[Challenger-II]

More Info would help all of us!! Was it a drop in pressure under certain conditions such as cold starts or after you were up and running?? Mine drops in half after cold startup but then recovers to normal after several miles. Funny thing is it starts up with normal pressure and drops when I leave the driveway. My original pump on my 99 was leaking from day one and was replaced at less than 1,000 miles on the clock, Now have 51,000 on its replacement.

 

[Cliffman]

Cold weather pressure

I for one have higher pressure when it cold, 12-13 psi at idle. When the truck warms up I get 11-12 psi at idle.

 

[Challenger-II]

Re: Cold weather pressure

Originally posted by Cliffman

I for one have higher pressure when it cold, 12-13 psi at idle. When the truck warms up I get 11-12 psi at idle.

You must be reading your pressure pre-filter?

 

[Cliffman]

It is defiantly pre-filter. Is there a known problem with that setup Seems to me that if you have the pressure sensor post filter then your reading would be dependent on the fuel filter being clean. When the ambient temp rises the fuel must thin a little causing the pressure to drop. I could be wrong regarding the reason but in any event, I know that the warmer it gets outside the lower the pressure goes. Not by much though only 1-2 psi at the most and I’m talking a difference from 60 deg. to 90 deg. in the ambient temp.

 

[Challenger-II]

Cliffman..... The main reason people go post filter is that you are monitoring the pressure the Injector pump sees, which is why we are concerned about fuel pressure. It will also tell you when your filter is in need of a change.



I just saw where you are from, so you probably dont see the cold temps we do here in the North East. My pressure sometimes drops to 5-7 psi for a short time after starting on cold mornings (less than 30 degrees). It does recover back to 13-14 psi after several miles of driving. I believe it is due to thicker fuel having a harder time passing through the filter, thus dropping the pressure.

 

[Cliffman]

Post & Pre-filter #'s

Has anyone bothered to check pressure on both sides of the filter? In other words, is there a difference in pressure when the filter is clean if you have a post filter setup? Reason I'm asking is maybe that's the reason we're seeing such a variation in psi #’s being posted. I have 12-13 psi at idle and 10-11 when cruising and 5-6 at full throttle all pre filter. This hasn’t changed since the new pump was installed. .

 

[Steve St.Laurent]

I monitor both and with a fresh filter there is no difference between pre and post filter numbers. You're supposed to change the filter if there is a 5 psi difference between pre and post, personally I change mine at at 2 psi difference because I've noticed some performance degradation above that.

 

[Cliffman]

Senser location

That's not a bad setup Steve. How often do you change your filter based on the 2 psi drop and how many pumps have you gone through if any?

 

[High Voltage]

My original pump (61510B29A stock# off side of pump) was repalced at 12k last oct... idle 9-10 wot 0.



New pump (3990105 ) as of today with 17k... 15-16 idle wot 9-10

Build date for new pump is Sept-21-01.



Fuel pressure gauge is off the VP44 pump.



hutch

 

[Cliffman]

High Voltage, are those #'s post or pre filter?

 

[Fiver]

Local dealer (Dodge) just replaced mine this morning, 10psi @ idle and 2 wot. Had no symptoms but I had a hunch after reading these threads. Told a small story to get the dealer to look at it under warranty (34. 5k miles now) What an awesome site this is. By the way, does anyone know the Dodge revised number (if there is one)? They installed a 5080885AA lift pump in mine. Cheers!

 

[High Voltage]

Cliffman, the numbers are post filter off the vp44 at the Schraeder valve...



hutch