Rapid fuel leak down help

[shovelracer]

I just picked up a 01 2500HD 6.0L w/ 160K miles. It ran strong for the first 2 weeks. I decided to change out the fuel filter and fuel regulator along with someother regular maintenance stuff. I also added a bottle of injector cleaner. 3/4 way through the tank of gas I started having fuel problems. It wont start but turns over with plenty of gusto. I cycle the key a few times and it starts. Sometimes it is more than others. I realize that this is common for these vehicles. The fuel pump was supposedly replaced 30K ago.

I have since checked the entire system for leaks, non. The flow is good. I removed the pump and inspected it, but it was clean and appeared to be working fine. All signs point to a bad check valve. I did a pressure test and here are the results: The system holds only 5PSI. The regulator is good/new. The pump builds up pressure during operation fine. It takes 5-10 seconds to leak down from 50 to 5 psi.

Here's what I dont get and why I am writing: During the pressure leakdown I can hear the pressure being released on the passenger side of the engine around what appears to be either the evap or egr lines. All I can figure is that the pressure is leaking back into the tank, out through the evap system and into the manifold then finally out the egr system somewhere. I have an external check valve I will try to install to see if this helps, but I am slightly boggled. Please help.

[shovelracer]

Tested the pump alone: 0-80 PSI instantly, 80-5 PSI in 5-6 seconds. Bad check valve? Pressure does not appear to leave via the EVAP. So I am not sure what I am hearing in the engine. The leak down does change with the temp of the engine. It is almost instantly when hot and slower when cold. I am installing an external check valve as the pump works fine and is only a year old. I own chevy, ford, toyota, and VW. This truck is the easiest to work on, but costs the most keep on the road.

[rjeffery]

I had the same problem on my 02. Determined it was a bad check valve and replaced the fuel pump. Now it holds pressure like it should.