Engine/Transmission (1998.5 - 2002) 2001 fuel bleed problems

[Kalaehina]

Would the return line at the back of the engine cause this as well? Or mainly the one coming off of the VP which I replaced.

 

[JR]

The overflow valve is threaded into the VP at the return line. And you replaced it and are still having this issue?

How is your fuel pressure gauge hooked up? Are you using an electrical or mechanical gauge?

 

[Kalaehina]

Yup new overflow valve and both electrical and mechanical gauge. Electrical from the top of the filter housing and mechanical reading from the schraeder at the VP. And both are giving different readings. Electrical reads higher. Yes it's confusing me as well. Also no stumble and no more codes.

 

[JR]

I would be hesitant to drive it for fear of roaching that new VP until you figure it out... .
I am not familiar with your model FASS, is it adjustable? Is it possible the adjustment is cranked way down which would explain the good pressure when bumping the key but when the truck is running the pump is not able to supply adequate fuel? Kind of grasping at straws here.....

If nothing else you may consider calling FASS and talking to them about a possible faulty pump... .

 

[Kalaehina]

It's a FASS DRP pump not adjustable. I have a Vulcan fuel line that goes from the filter to the pump standing by. I'm thinking of untying it on to eliminate that possible restriction

 

[hcole]

OK, Kal, this indicates to me that you have a SEVERE restriction somewhere in your fuel line. Your pump builds pressure as long as you have NO flow. When you ask it to actually flow some fuel, then it drops pressure as the VP44 is calling for fuel at the injectors and the return line. Try this. Disconnect the fuel line at the lift pump intake and run a rubber fuel line to a bucket of fuel and pump from this. If after starting the truck the fuel pressure stays high, then you have a restriction on the Suction side from the tank. If the pressure falls to nothing then you have a restriction on the fuel filter up to the VP44. As you experiment with this remember - do NOT pump any fuel to the VP44 that has not gone through the filter. I think you'll find the problem on the suction side of the lift pump. Good hunting and keep us updated.

 

[Kalaehina]

Thanks for the advice, I'm going to give this a try tomorrow. It's been a slow process the last month and a half since I can only work on my truck on my days off which has only been 1 a week, but I have a feeling I'm on the home stretch since there's not much left in my fuel system that I haven't already checked or replaced. But at this point a restriction somewhere seems to be the final culprit, now just to narrow down where it is. Hope I can finally resolve this, or I may have to bring my 96 out of retirement!

 

[Kalaehina]

That seems to have done it! Did the fuel check by using a fuel can as a replacement for the tank, and the pressure flew right to 15 psi! So I cleaned the lines coming from the tank, and even cleaned out the in tank unit strainer. Thinking about replacing it as cheap insurance as well. Btw tank work is made so much easier then my 96 since this truck has a dump bed! One last minor leak to take care of and I think I'll be back on the road, the Vulcan line I installed between the filter to the injection pump has an elbow with a pressure reading port, non Schraeder valve type, I think I need to seal it as I noticed a drip coming from it after my test drive. But at least I was able to drive it! Whew! What a month and a half it's been! Thanks for all the advice, info, and suggestions, at least now my fuel system is over 50% brand new haha! Thanks again guys!

 

[Kalaehina]

As far as the Vulcan line between the filter and the VP, the elbow at the VP has a port for fuel pressure hook up. Are those threads considered pipe threads? The instructions boldly say no sealant should be used, but in the section that talks about hooking up a gauge it says to use thread sealant?? I don't have anything connected to that port but I believe that's where the leak is coming from, just a drip, but should I cinch it down tighter or seal it? It also has a cap for the tapered end.

 

[Sticks]

I'd have to see this "Vulcan" kit you are talking about. No thread sealant on the Banjo bolts, but pipe threads typically need to have it.

 

[Kalaehina]

I'll try to get a pic, it's the one Genos sells, big line (1/2 inch) between fuel filter and injection pump.