Engine/Transmission (1998.5 - 2002) 'parallel lift pumps'

[RThompson]

I have spent considerable amount of time reading about the VP44 and the lift pump problems that go along with the 24 valve motor. Seems like a lot of money and some very serious research has gone into getting a consistent flow to the pump.

I need to throw my . 02 worth in to see if parallel pumps have been tried by anyone.

Would relocating the stock pump to the tank area and adding a 2nd stock pump next to it maybe work? Wire both pumps thru a relay, with the backup pump wired thru a normal open 5 psi pressure switch downstream from the filter. Theory here being, if presssure drops, the backup pump kicks in. This plumbing setup would need check valves to keep fuel from looping back to the tank thru the backup pump. A warning light could also be wired in when the backup pump kicks in.

Maybe check valves would put to much resistance in the fuel flow.

Someone experienced with low pressure check valves can perhaps answer this. Oo. Oo.

 

[Un-Hemi]

Since nobody else has anything to say about this, I'll offer my opinion:



If I understand your idea correctly, when the outlet pressure of the first lift pump drops below 5psi, the relay is energized through the N/O pressure switch and the second lift pump comes on line.



Some things to consider:



1. The relay must be held energized (latched), or the relay will cycle with the rising pressure from the second pump. This can be done.



2. When the truck has been shut off, the fuel pressure is 0psi. On startup, the pressure sensor/relay circuit must be held off until the fuel system stabilizes.



3. A fuel pressure gauge and a manual switch might be preferable. Pressure trends would be observed on the gauge and momentary drops in pressure wouldn't nuisance-trip an automatic relay. The second pump could be cycled periodically to ensure that it is functioning.



4. Gerotor pumps, because of their construction, would probably not require check valves, but they're expensive. Pressure loss through a properly spec'd check valve would be minimal.



It's an interesting idea, in my opinion. Some might consider it a belt-and-suspenders approach, but at least you wouldn't be out there in the middle of some rain/snow storm crawling around in the muck on your back changing the relocated lift pump on the side of the road!



It would be up to the individual to consider the cost vs. benefit.

 

[RThompson]

TommyTurbosaurus, thanks for the imput.



Getting ready here for a road trip and that d___ lift pump thing is still in the back of my head. 22,000 miles and still have 14 - 16 psi but I still have concerns about LP failure out in the boonies.



Went to a Cummins seminar for the 2003 ISB, at the Q and A portiion I asked the question to Cummins rep in regards to the short lived lift pumps. Seems that they are aware of our concerns but there is no official position at this time on what will solve the problem. He did take my E address and told me that a Cummins tech would contact me about a bypass system he is working on for CTD owners. This system is not endorsed by Cummins or Dodge and is in development. I hope we can encourage the developer to post on this forum about his system.



Any more thought on dual pumps?

 

[jwilliams3]

RThompson,

Take your trip, do not worry.

14-16PSI at idle are signs of a lift pump that is working just fine and is brand new.



People that are having most of the pump trouble these days are from modified trucks that can use up all of there fuel pressure after a full throttle run (like me) or a truck with an early VP44 (like me).



Your idea for 2 pumps running is a good one, but I think running 2, one at the cell and another in its home is a good way to have a constant pressure at the engine, but I do not think it is warranted for an unmodified engine.



My VP44 is still runnin strong! (knock on wood)



I would not be so paranoid about a stock truck!!

Bye the way too much pressure will kill that pump too!

A good constant supply of fuel is what that pump likes.



--Justin