2000 Dodge with the Cummins 24-valve ISB. I have installed a pressure gauge between the filter and the VP44 injection pump using a brass tee. For several months the gauge at idle shows 16psi, running at 70mph under heavy load it may drop to 11psi. Recently, the gauge started dropping to 6psi and sometimes under deceleration it won't come back up to 16psi. If I'm running down the road at 70mph, gauge showing 6psi and I depress the accelerator the pressure jumps up to 14psi but as soon as you ease off it drops quickly down to 6psi again. There are times when the gauge bounces back it forth from 6 to 14 psi quickly. I change the oil and fuel filters every 5,000 miles since new and it has 112500 now. I use only mopar or fleetguard filters. The dealer replaced my lift pump a few months ago.

I sent the above message to Cummins and all I got back was make sure you have clean filters and where to locate a Cummins dealer.

My gauge is a mechanical type so there are no electrical issues. So long as I stay at or above 5psi I know I'm ok but I don't like being that close o the red line. Any ideas?

 

Did you run it past any of the guys at www.dieseltruckresource.com ?

There are members there that know much more about diesel trucks than the people that normally post here...since that's the only thing they talk about there.

 

Thanks for the link
I received another responce from Cummins and they said the pressure is acting normaly. There words: Most people never see the pressure of the lift pump, but the lift pump is controlled by the ECM. The ECM will cause the pressure to go up and down depending on the load and speed of the engine. Cummins says that as long as you have some pressure the VP44 will be fine. If you lose all pressure and the engine is still running damage will accure. I guess that's why they sell idiot lights with a 3 1/2 pound sending unit on them.

 

what is the right pump pressure that delivery the lift pump and ram 2500 , 2000 have a pump in the tank.

 

The lift pump (carter I believe) on the 24 valve is notoriously poor quality and a commonly failed part.
I would change the fuel filter and pick up a spare pump. I think you areon borrowed time.A weak pump will accelerate wear on the lift pump as well as causepoor performance.
I'm pretty sure lift pump pressure should stay pretty constant within a few PSI. The gauge like you have is an excellent idea. most people don't realise they have a problem 'till it too late.

 

Thanks for your comments , did you now what is the right pressure on the lift pump and in my truck ram 2500 ,year 2000. have a fuel pump in the tank or only have a lift pump.

 

You said that your lift pump was recently replaced? If so did you take it to a Dodge dealer? Dodge will not replace it with the Carter pump any longer due to the high failure rate and the damage it can cause. Dodge probably replaced it with one that goes in the tank, the 6PSI crusing down the Hwy is normal for this type of pump. The bad news is that it is just as much a piece of cr@p as the original one.

If you have one that is still located up front by the fuel filter, you need to replace it as fast as you can. If you lose fuel pressure and run it dry, the VP44 will fail and then you are looking at a $2000+ job to get it fixed.

The popular pump of choice over in the CTD forum is the FASS or Walbro lift pumps. They cost a little more, but you won't have to worry about it again.

 

Thanks, Cowboy Bob, tomorow i going change a lift pump for a fass systen , bougth tuis truck 2 weeks a go , and have a new vp44 but the lift pump look old.
I dont take an risk, thanks for our help.
Eric,