Engine/Transmission (1998.5 - 2002) Key on Lift Pump PSI

[Cobra]

Lift PUmp

CMJCMJ

I wouldn't jump to a pusher pump just yet. Not long ago I read that the pusher sullies too much pressure and it can harm the VP44. Nothing definate on that but that was what I read.

 

[Cobra]

please excuse the spelling in my last thread. I am extra ordinarilly tired tonight

 

[Steve St.Laurent]

There has been ONE bosch engineer that said that anything more than 12 psi could damage the VP44 - that was at the TDR nationals last summer. He didn't know what to say about the newer lift pumps from the factory putting out 15 psi though. When I put the pusher pump on my truck I talked with the lead engineer at Dodge and at Cummins responsible for our trucks and they both said that the more the better up to a point and that 22 psi was no problem (on my truck with a 7 psi pusher plus the 15 psi factory pump I get 20 psi). The only potential problem they said with higher fuel pressure could be a hard start problem with pressure over 7 psi (that's the reason for the reduced duty cycle during cranking on the lift pump). If I try to crank my truck while the lift pumps are running it will take a second or so for it to start versus instantly if I wait for the lift pumps to stop (lift pump only runs for a few seconds after turning the key). There has been zero reported instances of a VP44 failure due to the additional of a pusher pump on here. Take that for what it's worth.

 

[Wolfgang]

Does any one have a part number for the pig tail harness?

 

[ehenry]

pigtail-4025182

lift pump-3990105

 

[mpjmpj]

Gave the Cummins shop my engine serial number and they gave me the part numbers listed above. I put the harness on anyway. It's $7 but I don't think it was needed. The original connectors fit fine, but the parts guy said it was needed.



I disagree, but it's in and works great (less one banjo washer that fell somewhere in that void).



Word to those who are installing one for the first time: take the washers off of the banjo bolts right away so you don't lose them like me and a few others.

 

[terrywerm]

I have not yet had the chance to add my FP guage, but hope to very soon. I do have some suspicions that mine may be acting up, but not sure.



I have a question for those of you that have experienced the erratic LP operation: Have you noticed that the engine gets much quieter (much less rattle) when the LP pressure drops off? I've had a couple of experiences where the engine would get notably quieter than normal - and it would do this for a while, several minutes anyway. She didn't seem to have lost any significant power, but after several minutes the engine rattle would come back to a more normal level.



I've experienced this a couple of times now, once after driving for about 30 minutes, and once after driving for well over an hour, and I'm trying to figure out whether it is normal, and if not, what is causing it. Thankfully it doesn't do it very often.



Terry