stinemonster

I have a 93 GMC with a 5.7L TBI truck I bought for a backup while I was replacing my motor in my 2001 Silverado.

About a month ago I ran it out of gas and coasted into a gas pump. Put gas in it and it wouldn’t stay running after that. If I kept pumping the gas it would run but like crap. As soon as I let off the gas it would die. Got it out of the Pump at the gas station and replaced the fuel filter in a parking lot. Didn't help. Finally had to get it towed home. AAA Plus is a life saver.

The fuel pump works but sounds like crap when you first turn the key on. It runs a few seconds then cuts off like it should.

After letting it sit there for a couple of weeks I finally started trying to get it going

I broke the fuel line loose from the fuel filter so I could pump the gas out of the truck and into my other truck. Hooked a fuel hose up with an inline filter to the trucks fuel line and turned the key on. The pump pumped for a few seconds then stopped. Just as it does every time you turn the key on. I had to turn the key off and then back on to get it to keep pumping. The pump had pressure but would still stop pumping after a few seconds.
It doesn’t appear the problem is from the fuel pump. Without pressure on the line shouldn’t the fuel pump keep pumping?

I changed the fuel relay and it didn’t help.

I changed the diaphragm out in the pressure regulator. It didn’t help much. The truck will run better as long as I keep pumping the gas but as soon as I stop it dies. Almost is if there is a kill switch.

When you turn the key it will start up. It is TBI. You can see a perfect cone of spray coming for the TBI and then it just dies out.

Anybody have a clue of what is wrong?

racerx55

alot of times when you run them out of gas it kills the pump, even if it runs. you need to check the fuel pressure. im thinking TBI should be 9-13 psi. The pump wont continue to run unless the engine is running. it doesnt shut off by pressure, its just activated by the ECU for a couple second with the key on to prime it. By what your saying it sounds like a low pressure problem - bad pump. have a look at the pressure. ive gone through quite a few pumps on my old TBI truck and it was really similar to what your saying, and sometimes even intermittant.

stinemonster

Thanks.

I will go back to my original plan of pulling the gas tank and changing the fuel pump. I was hoping it was something easy.

Blindsight

Yeah, it seems that if you let your fuel tank get really low [like ridiculously low to where it can barely pump] really often, you will burn through fuel pumps like no other; it is essentially trying to pump with nothing in it, and zero lubrication, and they just burn themselves up. It's sort of like turning off a turbo'd vehicle before the turbo stops spinning.

lukemoore646

i had an instance on a 2000 with a 4.3 that would not start with 50 psi because it required a minimum of 65 psi

ukrkoz

yeah, back on old cars, they used to have sort of breather tube on top of the fuel tank. one could pump up tire tube, hook it up to that tube, and positive pressure will push fuel into the fuel line. he-he.

btw, most agree it's much easier to slide truck bed over to the rear to get to pump.

lukemoore646

i agree on removing the bed, unless it is owned by a farmer, then it is usually full of shtuff

ukrkoz

case of beer will call neighbors just like this....

lukemoore646

i have used a car hoist to remove the box before, works pretty good if your carefull

Blindsight

Or as my friend and I did; MAN POWER! Haha, His father, brother, himself, and I lifted his truck bed off so he could change the fuel pump. My uncle changed my fuel pump by dropping the gas tank; both were finished in about the same amount of time, so it depends on how much work you want to do, really.