6.5 td champ then not

[davscript]

I have a 1999 chevy k3500 that I use for plowing. this year it has run great for about 2 hrs the runs itself out of fuel. I can get it running again but only a couple hundred feet at a time when it sits for 5 or so hrs starts up and rund like a champ again. have changed a bunch of electrical stuff to no avail. lift pump, pmd,ops, checked grounds ect still does the same. any good ideas

[sctrailrider]

Try leaving the fuel cap loose, see if that helps any.. sounds like a filter might be close to needing changed or the LP is not really pumping fuel. Do you have a fuel pressure gauge??

[davscript]

Changed filter bunch of times thought it was gelling by it was not the case. Don't dare leave cap loose its a dually and the fuel fills just hang out there I did swap caps around frt to rear . I don't have a fuel ga but when the it runs out of fuel the lift pump only Pumps a sec then shuts off I have to cycle the key a bunch of times to get it to start again

[a5150nut]

If you ran a tank out of fuel, did you bleed the injector lines afterwards ?

[davscript]

The tank was never run out of fuel. the filter housing (fuel manager) goes dry. and to answer your question yes bled the lines. Acts like to me whatever tells the lift pump to pump is telling it that there is enough fuel pressure and not to pump. We have changed a lot of electronics not sure were else to go

[DmaxMaverick]

The tank was never run out of fuel. the filter housing (fuel manager) goes dry. and to answer your question yes bled the lines. Acts like to me whatever tells the lift pump to pump is telling it that there is enough fuel pressure and not to pump. We have changed a lot of electronics not sure were else to go

The pump doesn't run "on demand". Once engaged, it runs continuous (or is supposed to). Engagement is controlled by the PCM, then through the relay. If the filter bowl is less than full, all the time, look for electrical connection problems, pump relay, grounds, and of course, a leak between the lift pump and tank. If it's very cold, your fuel viscosity may be marginal. Increased viscosity will exploit the smallest of leaks, that may not leak at all under other conditions. Keep your diagnostics simple. If the filter bowl isn't staying full, something is impeding the fuel flow while the engine is running. A leak is most likely.

[davscript]

When the engine stops the filter is empty and when I turn the key fuel pump will just stat then stop changed relays

[More Power]

When the engine stops the filter is empty and when I turn the key fuel pump will just stat then stop changed relays

The 1996+ lift pump will run for ~20 seconds when first turning the key from off to run (like while waiting for the GPs to cycle) then it'll stop if the engine isn't running. The lift pump is supposed to run continuously whenever the engine is running.

Pressurize the fuel tank using 5 to 10 psi, then look for a fuel leak from the tank to the injection pump. Under pressure, at the fuel tank filler neck, fuel can leak at a bad spot in the hoses/lines that might be the source of an air leak. Jim

[Freddyack]

Plugged tank sock?

[davscript]

Well tried taking caps off and even HotWired the pump to make sure it wasn't a bad wire and still after 1 1/2 he's she started fluttering and filter went dry???????

[sctrailrider]

Disconnect the fuel pump and blow some air through the line back towards the tank to clear the sock.

Then, make sure the fuel pump is really pumping fuel, just because it rattles doesn't mean it is moving fuel.. and it may only be moving "some" fuel, just not enough..

If the FFM is empty something isn't working right..

[Dvldog8793]

I had a similar problem, I used a fuel pressure gauge taped to the windshield while I was using the truck to diagnose a flaky lift pump. It would go fine for an random amount of time (sometimes days, sometimes minutes).

The gauge line was hooked up to the bleed valve and gauge was taped to the windshield. It took me about a day to see what was going on. The pump would work fine and then randomly cut out completely or maybe drop to 1psi or less. This would cause all manner of issues....misses, dying, lack of power....ect.

The solution for me was replacing the lift pump and cleaning all connections/grounds. I ran with gauge again and never saw the problem return. IMHO....don't waste any money on a cheap pump...buy a Delco.

If you blow out the sock, make sure the cap is off and use low pressure...20-30psi.

I think the gauge and tubing cost about $30.
Good luck, hope this helps.

[huntinlife1993]

I dont know if you have tried this but maybe check your relays? And fuses

[arveetek]

Plugged tank sock?

This could definitely be your problem. I chased a similar problem for months before finding out that the fuel "sock" inside the fuel tank (precleaner, screen, etc. located on end of fuel pickup tube) was sucking shut. My engine would start great, run for about 7 miles, then die of fuel starvation. I have a fuel primer switch that forces the fuel pump to run, and I could not get fuel to pump into the filter housing. Let it sit for a few hours, and everything was ok again.

Turns out the cheap aftermarket sock on my newer fuel pickup assembly broke down and would actually suck shut after a while. Letting it sit allowed it to relax and then allow fuel to flow again for a short time.

I replaced nearly every fuel component before figuring this one out.

Good luck,

Casey

[davscript]

Thanks for all your inputs I removed the lift pump and blew back towards the tank to clear the sock and this round of plowing I have had no problem I'm guessing the sock was failing thanks again

[DmaxMaverick]

Thanks for all your inputs I removed the lift pump and blew back towards the tank to clear the sock and this round of plowing I have had no problem I'm guessing the sock was failing thanks again

Unless you have replaced your OEM sock/sender with a [defective] aftermarket, the sock didn't "fail". Your fuel supply failed. The sock will do what it's designed to do. If it "fails" (plugs), then the problem is the fuel, either contaminated or frozen, not the sock.

[davscript]

Assuming that the sock (failed ) in my words meaning yes it did its job and in blowing the crap off it now I know that my next step is getting into the tank and cleaning it out. the truck has a tool box over top of the tank so we needed to know were to go before we unbolted toolbox off the frame cause that's a pain.

[DmaxMaverick]

Very good. Seems you are trying to diagnose the right end of the problem. Removing the bed from pickups isn't difficult. Utility beds, not so much. Good luck!