2nd Gen Non-Engine/Transmission Fuel pressure

[DNewell]

Okay guys, I've got a question that is sure to draw some fun responses. I got to thinking about my issues with fuel pressure and the fact that my truck ran without any pressure from a bad LP. I've now got a new LP, and my pressure averages about 10psi. WOT is lower, but on average is at 10. Some guys are saying this isn't good enough, and some are saying it's fine. What does it matter. If my truck runs well off of next to nothing from the VP44 vacuum, why would higher than 9-10 be necessary? Can someone extoll the benefits and virtues of running really high pressure to the VP44?

 

[bmoeller]

From some of the reading I've done, as long as you don't go below 8 psi @ WOT, you should be fine.



The thing with the VP44 is, that the fuel also lubes and cools the pump. They aren't lubed by engine oil, as the P7100 is, and maybe the same for the VE. Not 100% sure on the VE, though.

 

[NLofton]

Just replaced my lift pump also, was down to 10 idle 8 wot, New pump 16 idle 14 wot. I would much rather change a lift pump than the expensive VP44.

 

[dresslered]

This is a loaded question and I am sure that I will get some flack on my opinion. First off, where are you taking your pressure readings? If you are seeing positive pressure prior to the fuel filter, you still can be getting no pressure (or not enough flow) at the injection pump due to a dirty filter. Ideally, you want a positive pressure at the injection pump. Under most circumstances, any positive pressure at the injection pump is in the "safe region" However, a lift pump that is only achieving minimal pressures is obviously on its way out and should be replaced. I would say that 10-psi is fine for now (normal for stock fueling), but if you start reading lower pressures down the line, I would assume that your lift pump is on the way out. Sometimes this is instantaneous, other times it slowly degrades over time. Never allow zero pressure at the lift pump! My fourth lift pump is putting out a strong 15-psi most of the time which I have never seen, but I can drop it down to 10 with my mild upgrades and a heavy foot). Hopefully, I will see more than the typical 25k-mile replacement interval under my moderate fueling enhancements. My best advice is to keep a spare under your rear seat as there just is no telling when these things are going to krap out.

 

[dresslered]

Just replaced my lift pump also, was down to 10 idle 8 wot

I've seen this on brand new lift pumps. Better safe than sorry.

 

[NLofton]

I've seen this on brand new lift pumps. Better safe than sorry.

Thats right, Since the truck has 143000 and looked to be original i figured i was pushing my luck