Flatty

So I installed the fuel pressure gauge today, and I am confused on the #'s I am reading. Here is what I get:

At idle, I am reading 14-15lbs
When cruising normally, that drops to about 10-11 lbs (this is driving down the freeway with the other cars, not really getting on it, but there is throttle being applied)
Now when i really get on it, and open him up, I go down to about 7-8lbs...

So what is my WOT reading? Is WOT Wide Open Throttle, or is it While On Throttle?

Are these readings right? Should I be shopping for a new IP?

Thanks
Dima

phox_mulder

Those readings are right on the edge.

Idle is right on, cruising shouldn't drop much below 11-12, WOT (Wide Open Throttle) you don't want it to drop much lower than it is, 5-6 is pushing it.

Some would say any pressure is good enough, if you show pressure that says the lift pump is supplying more than the VP44 needs.

Personally, I'd change the lift pump and keep your current one as an emergency spare.


phox

Flatty

How do I know when the lift pump is bad VS the Injection pump (VP44 right?). I know these questions probebly sound DUMB, but I am kinda new to this diesel thing. Also is one lift pump better that another? I have been hearing about hte FASS ssytem. What do I need to make this work and save the VP44.

Dima

Beast2B

fuel pressure won't give you much indication of the status of your vp44. it is monitoring the feed pressure to the vp, therefore it is a preventative measure. "any pressure is ok" is WAY OFF of accurate, because the vp44 uses the flow of fuel to cool itself. all of the fuel not used for the cylinder is returned to the tank. if you have only enough fuel for the combustion, you WILL overheat the injection pump eventually. FASS, Airdog, pusher pump setups... lots of options for upgrading the fuel system, probably depends as much on your budget as much as benefit.

Shovelhead

A partially clogged fuel filter will sometimes give you a low Wide Open Throttle fuel pressure reading.