I’ve got one for the books...
This problem started about two months ago when I was getting on the hi way pulling a trailer. My truck fell on its face and lost a ton of power. I had to feather the throttle to keep it moving but not hiccupping. It felt like I was running out of fuel. I also noticed that my normally loud and somewhat consistent FASS 95 fuel pump was all the sudden very quiet, just a light hum like the electric motor had no load on it. I limped it home and messed around with it for a few hours completely disassembling, inspecting and cleaning every part of the pump that could be removed. After several attempts to get the pump to pump out of a bucket (bucket test) as per FASS technical support (whom I was talking to constantly)I finally got it to work and put it back on the truck assuming it was some fluke.
Two weeks later the problem arose again, so I once again removed the pump and messed with it for hours. I finally decided that the pump must be bad. Since the pump was supposedly still under warranty I took it to my original FASS installer and had him diagnose the problem. He confirmed that the lift pump was producing no pressure thus verifying my warranty claim. (150 bucks to have someone agree with me)
I decided to replace the pump myself to save a buck and limped it home. I called FASS and explained my problem. They told me to send them the pump and when they themselves could confirm that it was the pump they would send a new one. Well I could not wait the two-three weeks for that process so I bought a replacement pump (electric pump that bolts on top of the filter housing) for $275+shipping so that they could credit my account when they found the pump to be bad. . I threw it on the truck and it ran fine.
One week later I had the same problem again. I did the usual routine of checking fuel pressure with a gauge, removing the pump, confirming that it did not pass the bucket test, and calling FASS. After a few more hours they finally agreed to send me a used pump that they were sure was working. So I paid the 60 bucks shipping and put it on the truck the next day. It worked FINE.
1-2 weeks later, you guessed it SAME PROBLEM. So I thought maybe it’s something in the fuel tank. So I removed the tank and it was relatively clean, but I installed a Vulcan draw Straw kit to eliminate any possibilities of clogging just as insurance. I also replaced the cp3 pump, overflow valve, and a bad injector for a separate problem that same day. I replumbed most of the low pressure fuel system (not the return) with new hose. I put it back together and the truck ran for another week.
At this point I was fed up and bought a complete System from Air Dog. I put it in with my own hose (I confirmed that the hose included in their kit is not Biodiesel compatible) and figured that this problem was behind me. I drove a good 750 miles last week.
Well yesterday to my surprise the truck did the exact same thing. I left my house in the morning and it ran ok while warming up. After it warmed up I put my foot into it a little bit and it ran out of fuel. I limped it home and pulled the Air Dog apart to see what I could see. Again it looks completely fine and with some fiddling I can get it to pump just fine. I know that if I just prime it and put it back on that this will just continue to happen periodically.
I have talked to several local mechanics as well as tech support from FASS and Air Dog and my brother who is a tractor mechanic at Fosters vineyards. Between my brother, dad, and myself we cannot for the life of us figure this darn thing out. It looks to be a simple pump. I am relatively mechanically inclined (built a few motors and cars) but this is beyond me.
If someone figures it out ill buy them lunch!! If you’re in Visalia…
Thanks for your time. (and sorry for the essay)

 

For what it's worth, I don't think the pump is the issue. It sounds to me like a similar issue I had on the '02 some years ago, where the lift pump would shut off. Turns out it was either an issue with the relay or the harness to the lift pump. You might want to check those things first. An easy test for that would be to wire your lift pump to run directly from the battery any time the ignition is on. (Maybe it already is... on a 2nd gen, it's controlled via the original lift pump wiring, through an additional relay).
Good luck!

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BTW

 

howdy i would have to agree that it most likely isnt a pump problem itself but sounds more like an electrical issue...sounds like when you mess with each pump it could be turning a wire or something in the harness just right to give it enough go. and then after a week or two of bumps from our terrible roads it loses some kind of connection or ground or what have you and its back to the pump again?

 

Ill try the relay. Ive checked voltages while parked but maybe its just an intermient electrical problem. Thanks

Any Others?

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My only concern with the electrical issues is that i still hear the pump running when this happens, its just really quiet like it has no load because it lost its prime

 

or possibly a bad connection somewhere that is not allowing it to recieve full power? use a voltmeter and check the voltages

 

Are you sure that your pump is not shutting off for say 5 or 10 seconds just enough for the CP3 to suck air in through the pump assembly through the return line or something. It is just a thought.

 

i would have to agree wit everything u guys have said i would start checking the wiring and if the pump shuts off for a short period of time then it would allow air into the lines try running all new wire from the fass pump to a power source and hard wire it to the battery with a switch on it so u can shut it off and see if the truck runs normal again an go from there