Engine/Transmission (1998.5 - 2002) 2nd gen fuel question, details

[Dieselisbetter]

2000 Ram 4x4 diesel 5spd long bed ext cab.
353,000 miles runs great.
All stock, just fuel pressure gauges, one on vp44 and a in cab digital gauge mounted at bottom of fuel filter.

This truck has a Carter lift pump at the block near fuel filter along with a in tank pump.
New pressure release valve on vp44.
Diesel kleen and occasional 2 stroke oil.

Not sure how or who installed this configuration, possibly a dealer add on back in the day.

Im getting 9psi all day long. Wide open it drops to about 8psi.

Im thinking about adding a high volume lift pump to replace the carter lift pump.

Can this be done without messing with in tank pump?
Should I pull the in tank and add a draw straw?
Can a draw straw be added without removing the function of the in tank pump?

Of course im on a bit of a budget and would prefer a Fass system and be done with it.

Any advice would be appreciated.

Id normally just ask Forrest since he was the one who turned me onto the Cummins diesels way back when.

 

[GAmes]

Why would you want to do anything if it runs great?

 

[BarryG]

Agree with GAmes. No need to do anything. Regardless of what you have been told or read on the internet about vp44 fuel pressure needs. If you are getting 9psi and only drop to 8 psi at wot. You are totally good. The VP just needs positive pressure doesn’t really matter how much as long as it is positive at all times

 

[petersonj]

There is no immediate concern - as @BarryG states, as long as there is a positive pressure at the VP44 injection pump inlet under all driving conditions, all is well. The VP44 internal fixed displacement vane pump (called feed pump by Bosch) does all the work - the lift pump just ensures that there is plenty of fuel available at the VP44 inlet.

However, if this were my truck, I would want to know what is powering those lift pumps. On the OEM fueling system, the ECM directly powers the OEM engine block-mounted lift pump.

If during the life of the truck, Daimler Chrysler warrantied a VP44 injection pump and installed an in-tank lift pump under the same warranty (this occurred with my truck), then a relay was added by Daimler Chrysler that was powered by the ECM. The block-mounted lift pump was removed.

I would not want the ECM directly operating two lift pumps. If the ECM is triggering the coil for a lift pump relay for both pumps, then that would be okay.

If one or both of the pumps are wired directly to an ignition switch source, then there could be a safety concern should the truck be involved in a serious accident, which could result in a leaking fuel line with a continuously running lift pump.

Also, when a lift pump failure does occur, it will be more difficult and time consuming to diagnose which pump failed with two lift pumps in the circuit. When one lift pump fails, that pump is likely to become a restriction resulting in making it harder to diagnose.

- John

 

[Ozymandias]

The system works perfectly fine - never mess with a running system.
Old but true.