I've posted this question on another board before, and possibly here, but it's bugging me and I can't get to the bottom of it. If anyone has any ideas I'd appreciate it.

Ok, when I first got my truck I put a BD warning light kit on it. Whenever I would turn the key on and wait for the "wait to start" light to go off the intank lift pump would build up enough pressure to turn off the warning light and that pressure would hold for a good 20 seconds before it leaked down enough to make the light come on again.

So I decided to put a holly on the frame and did away with the quick connect on the tank outlet and ran 3/8 line all the way from the tank, to the holley and up to the fuel filter inlet. Tha't when I started having the problem of pressure quickly bleeding out of the fuel system. I'd turn the key and pressure would build and within 3 seconds be back to zero. So I'd crack the inlet to the VP44 and bump the starter. You could hear air escaping and I'd tighten it when all the air was out. Now the system would hold pressure again. But as soon as I drove it around for even a half hour the pressure would drop quick again, and there was more air in the lines.

So I took the holley off and went back to the stock steel lines. Except now I have 3/8 inch line from the outlet at the fuel tank to the beginning of the metal line inside the frame, and from the end of the metal line to the inlet of the fuel filter. Every hose clamp is tight. I even disconnected the fuel line at the fuel filter inlet and pumped 5 psi of air pressure both going to the tank and going into the fuel filter to the VP. I had a gauge right on the air hose and bother directions had absolutely no leakdown. Put it all back together and blead it out real good at the VP. And it's back to the same thing.

Does anyone have any idea what's going on? It didn't act this way when it was stock, and it's just about back to stock now aside from the two pieces of 3/8 replacing the quick connects. But they're TIGHT. It's got to be something when the intank pump is running, maybe it's sucking up air somehow.

The truck runs fine but I know there's more air in the fuel than normal. That can't be good.

 

You can replace hose to vp44 with clear hose and verify air in system. There is a bleed off port on return banjo bolt. This will drop pressure after shut down. Pinch off return line to verify bleed. (don't leave) Frequent leak is at fittings of fuel tank. (pull bed). Fittings not tight, new hose leaking, tube cracked are some of potentials. Many times will leak vacaum but not leak under pressure. (go figure)

 

On the VP inlet, like the little piece of rubber hose right before the inlet?

Return line from the VP are steel lines from the banjo back to t T connector behind the engine. There's no place to put rubber on this line.

Where do you tighten these fittings at? There's the big cap that hold the whole sending unit in but the fittings that the hoses connect to for fuel feed and return look molded in. The hose is new and tight. I double check this stuff but if you have a picture or diagram that shows where to tighten that would be helpful.

 

I've had 2 problems with my in-tank module.
First was that the metal lines to the quick-connect fittings were rusted through.
The second problem was a lot uglier- the in-tank module has a suction line and this line had rubbed on a screw of the module. It was easy to find out that it was inside the fuel tank, the truck behaved fine if the tank was brimming full and the engine had been run for some minutes. (this had all the air purged.)

I don't know if the module is the same for your 01, but I'd suggest checking whether the problem goes away if you fill the tankk completely.

Just my 2c

AlpineRAM

 

That sounds like something to test... Next fillup I'll fill it full (ugh, that'll be about $150) and see if the problem is still there. The rusting through shouldn't be a problem, I'm pretty sure the intank was installed with the new VP in 2005.