A puzzle for you GM experts

Here's my problem: I have a 1996 K2500 Suburban, 5.7, 136,000 miles, automatic. It had been running great, but quit on the way home a couple nights ago, just like turning off the key. I have spark but no fuel. I had to have it hauled home. To add insult to injury, the guy driving the rollback backed into a tree limb while turning around and busted out the back glass. So now I have a three ton lawn ornament that leaks. Anyway, I couldn't hear the fuel pump run when I turned the key. I put in a new fuel pump relay and changed the filter and now when I turn the key on I can hear the pump running but still no fuel spraying into the TBI. It will start when I pour gas into the TBI, but quits as soon as that fuel is gone. I had replaced the fuel pump a couple years ago. This is my building material/coal hauler so I really need to get it running. Any ideas?

just guessing ....pluged fuel filter?
no gas in tank?

I'm a good one to assume it's the most expensive, hardest to replace part and overlook the obvious, but I put a new filter in, and have 3/4 tank of gas, so it's not going to be that easy.

do you have pressure in the fuel rail up to the TBI?

I don't have a pressure gauge, but when I push the valve at the test port, I get a good stream of fuel squirting out.

If you can hear the pump run, it is probably not a wiring/relay problem. More than likely the fuel pump is shot.

-Rob

Yeah but he said he gets fuel at the schrader valve. And he can hear his pump running. If there is pressure there it has to have pressure at the TB. Bad ECU maybe?

Those things are very picky about fuel pressure. It should be 55-65 psi .... any lower & it won't run, even if you have fuel.

Remember when a fuel pump was $15 and took 10 minutes to change???

Yeah, I'm seriously thinking about getting rid of the Sub and finding a 70"s Dodge Power Wagon; something as simple as I am. I've always liked the looks of those old beasts. Anyway, if it's low fuel pressure, would you think pump? Fuel pressure regulator? The thing that puzzles me is that it just suddenly quit with no symptoms at all. When the pump went out before, it ran poorly off and on for a couple months and never did die completely. Just makes me think electrical with it just shutting off like that.

Very well could be the regulator. Seeing that's cheaper & easier than a pump, I'd replace that first. Wouldn't hurt to grab a pressure gauge though before throwing parts at it.

Without test equipment -- you may as well play with your self and leave your credit card at the parts store

If you have pressure with the regulator stopped the pump is good - when the regulator is in line and pressure is bad - the regulator is in question

but it could be 12 other things too

See -- you need tools for any job

^^^ Very true!

I recall some of the S10's having a vacuum line to the regulator that you could disconnect, & see if it stalls or keeps running ...... but I'm not sure the 'burban has that ....

If it does, & you see fuel in vacuum line, it's bad.

two things well three

efi relay and or fuses two 10 amp ones
ignition switch
smack the ecm...

I believe its the ecm. A buddy of mine had the same problem with his Suburban. It was driving him crazy, just dying in the the middle of traffic. He replaced several of the common items mentioned above, until someone told him which part was causing the issue.
I'll get more details from him and post it here.

Edit: check for PMD failure. I think it costs about $80

I’ve had the same thing happen on my S10 Blazer, 1) was the replaced fuel pump Factory or after market? The 1st one I put in was aftermarket and lasted about a year it failed to make pressure, So the 2nd one was dealer part and that worked fine, I’ve heard that aftermarket one’s have a tendency to fail, it’s a 50/50 shot.

On the top of the engine there is a red wire (on GM’s) if you look in the shop manual you’ll should find it, it is to test your pump to hear if it runs, you can use this to test pump pressure to see if that ( aftermarket) pump is pumping.and at the specs.

Good luck
Been there