sgaynor5

I have a 5.3 vortec out of a 2002 Suburban in my 65 GMC. Sometimes while driving I loose power like I turned the engine off. If I let up on the gas it comes back and if i give it more throttle, it cuts out again. If i give it full throttle, it cuts in and out. If I stop and turn off the truck and turn it back on it acts just fine for another couple minutes to half an hour then starts acting up again. Seems to happen less sevearly with 3/4 tank to full tank and more under half a tank. Have the oem tank sumped with inline filter. Tried putting transfer pump to keep the inline high pressure pump primed. Fuel pressure while running is where it should be.

Horsepwraddict

iTrader: (12)

It deffinatly sounds like a fuel problem to me. Thats what new(ish) cars tend to do when they run out of gas. Check your fuel filter and flow your test your pump. Just because its making pressure doesn't mean its putting out the volume.

What are you using for a pump?

Old Geezer

iTrader: (3)

Tank vented? If so, is the vent large enuf?
Results of scanning are??

V8Rumble

iTrader: (9)

That's exactly what it sounds like to me as well - sounds like the fuel pump is pulling fuel out faster than air can get in to replace it. When you let up on the gas, it relieves some of that draw. Should be easy to test, you could either drive around just a bit with the gas cap off, or get a vented gas cap...

sgaynor5

No ses or codes in computer. The fuel pump i am using is an Airtex e2000. Is an inline pump that puts out 70-90psi and flows 30-40 gph meant for a ford truck application. I have tried taking the gas cap off while it was acting up and it made no difference and i have a vented gas cap on it now. After putting in the push pull pump to try to keep the pressure pump primed the acting up was not as bad or as frequend. My current idea is that I didnt get the tank cleaned out as well as i should have and there is a piece of rust or something that partially covers the pickup hole in the bottom of the tank and when i shut the engine off the obstruction moves and i can restart without problem. I am just looking for another possibility before taking the tank back out and cleaning out again. Thanks for the ideas. Keep them comming.

busta9876

iTrader: (3)

Did you check fuel pressure sitting still, just free revin' the motor, or during the time of the complaint. I find it useful to extend the line on fuel pressure gauge (using high pressure eif hose) and tape the gauge to the windshield where I can see it. Then drive it under the conditions, and reproduce the issue. If Rust is doing what you think it is, you should see a drop in pressure during the complaint.

Horsepwraddict

iTrader: (12)

where is the pump mounted in the vehicle. Is it below the tank?

sgaynor5

Pump is in frame rail bout 8-10 inches below bottem of tank. I took apart the screen filter between tank and pump today. There were pieces of what looked like the gasket from the sending unit. I changed the sending unit before starting to drive the truck. Some of the old gasket must have fallen in and been covering up the pickup. Wasnt getting those pieces till I put in the push pull pump. That pump must have been able to pull some of the pueces through. Doesnt act up as much now. I need to pull and reclean the tank. Will let you guys know if that takes care of the problem.

Thanks for the help

Shon Herron

iTrader: (25)

Did this get resolved?

bighaas79

Those older inline fuel pumps from the fords are not designed to be used alone. Ford actually used 2 pumps one in the tank, to supply volume to the one on the frame rail, and the one on the frame rail to pressurize. If you were using the frame rail one to pull the fuel and pressurize that may be the issue. I've had to work on a few of those and they were kind of a joke. And if either one isn't working properly the truck would run like crap. I'm not positive but i would think using a fuel pump better suited for your needs than the ford setup would make a difference. And really why use two fuel pumps when one, better suited to the aplication, would be easier? Just a note I've used replacement airtex pumps in the past and have had enuf trouble with them i will not use them anymore.

Old Geezer

iTrader: (3)

"Just a note I've used replacement airtex pumps in the past and have had enuf trouble with them i will not use them anymore."

I have had the same problems w/ those pumps. The last trip to my NAPA store, for a GM application, the parts guy refused to sell me 1. He sent me to the GM dlr, saying the aftermkt pumps may last a yr, 2 yrs, or 2 days.
That Fird system does not operate at the 58-62psi range, like the LS engines do, do they???

gofastwclass

iTrader: (2)

Word around the campfire in my area is they aren't worth the box they're sold in. Don't get cheap on the fuel delivery - they always fail at the worst possible times.

bighaas79

Don't know if any of you have access to a scope but i have seen waveforms on a new airtex that were worse than the bad pump.

ls1nova71

iTrader: (4)

I've never had any good luck with Airtex pumps, I replaced one on my truck, drove it literally .02 mile, parked it in a friends garage, and it went bad a coulpe of months later when he needed to move it, pump wouldn't come on at all.