Engine/Transmission (1998.5 - 2002) Fuel pressure

[LSchulz]

So I bought my truck off my dad in January (he got an '06), and put gauges on it shortly after (truck is stock). Once out of the shop, I had about 2psi of fuel pressure at idle, and nothing with any load on the engine. I took it to the local dealer, where they told me that it wouldn't run if the lift pump had gone. Long story short, I got them to take a look at it, and they ended up replacing the lift pump under warranty. The new one is relocated back by the fuel tank, rather than on the IP. The question is this: what should I be getting for fuel pressure? Currently, I get about 7psi at idle, and can maybe drop it to 4. 5psi at WOT. I'm not too worried, as it seems consistent (just ran 3100 miles with a trailer over spring break), but I was just expecting it to be higher.

 

[Oil Burner]

Are you sure you didn't get the new in-tank pump? Those pressures seem right in line with that setup.



I always replaced my factory pumps when I went below 5 or 6 psi at WOT. I never go below 12 now with the FASS.



The stock truck will probably run nearly normal with a bad liftpump and sometimes you wouldn't even notice it. The dealer is wrong about that.



Good luck. I have to think that the IP suffered form the low fuel pressure. Sounds like you still have a warranty so that will help if the IP fails.



Jason

 

[SHobbs]

If those pressures are correct it ain't good. At idle you should see 13-15psi and never below 5psi at WOT. Those numbers have been pretty much the normal for everyone with a 2nd gen. Your LP may be going by the way side slowly and the truck will run with a dead LP at the expense of the VP44 if you run it long enuff.

 

[LSchulz]

I'm not sure if the pump is actually in the tank or not. The service rep told me that it was back there though, it as it's been winter, and there's no shop space here at school, so I haven't been too eager to go crawling around underneath. All I do know is that it is no longer up on the engine.



And yes, it will run with a bad LP; mine ran for who knows how long with a dead one before I put the gauges on. The 7psi at idle is what it was coming back from Dodge with a brand new LP. I suppose there could be a gauge problem, but like I said before, things have been consistent, just lower than expected. I don't think that there would be a problem as long as there is a positive pressure on the line into the IP, and it is never starved for fuel. On that trip mentioned in the last post, I was running pretty hard on the interstate with a trailer (25+ whitewater kayaks, paddling gear... ), and was never able to get below 5psi or so, even at WOT on some pretty long climbs.

 

[ironbutt]

If the dealer did install the in tank unit, there will be a metal block mounted were the old lift pump was,and it will still have the restrictive banjo bolts.

If this is true then I would advise you to get a Vulcan big line kit and eliminate the banjos,and increase the flow of fuel to the VP44. ( a lot of people have this and it helps with the fuel flow. ) Good luck. "ironbutt"