96 K1500 Burb seems to not be getting fuel. Cranks but wont start. Need advice please

[8thNote]

So yesterday I had been driving the Suburban all day (5.7 Vortec) and made a stop at a store in the late afternoon. Came out to leave and it would not start. Battery is strong and it's cranks, but seemed to not be getting fuel.

So I had a friend take me home and I drove back in my other vehicle to work on it. It would run a few secs on starting fluid, so it has spark. I pressed the Schrader valve on the fuel pressure test port with a pick (don't have a fuel pressure test tool) and fuel shot up all the way to the hood, so it seems to have good pressure. And compression seems to be good while its cranking. I then replaced the fuel filter and the Burb immediatly fired right up and ran great so i thought i had it fixed. I poured a can of seafoam in the tank for good measure and drove it home and took a shower. Then I drove it with my wife back to the parking lot where I had left my other vehicle while originally working on the Burb.

My wife drove the other vehicle home and I decided to stop by the grocery store on my way back home (Burb was still running great at this time). I was in the grocery store 10 mins, came out, and exact same thing. Burb cranks but won't turn over. It was almost dark at this point and i was very frustrated, so I just had it towed home.

I've been at work all day today and haven't had a chance to look at it again. But I was wondering if anyone had any suggestions? It will hook up scan tool later, but there is no CEL on at this point. What would cause it to run fine for an hour after changing fuel filter but then suddenly not turn over again? This is my first Vortec GMT400, so I don't know alot about the fuel injection (yet).

Thanks in advance for help. I will update this thread as I go

 

[Caman96]

You really need to check fuel pressure.

 

[8thNote]

You really need to check fuel pressure.

I know. It's on my to do list. I'll pick one up a harbor freight or rent one from parts store.

 

[Caman96]

I know. It's on my to do list. I'll pick one up a harbor freight or rent one from parts store.

Free at auto parts store. I always find Oreilley’s has better quality “rentals”.

 

[Schurkey]

Burb cranks but won't turn over.

"Cranking" and "turning over" are the same thing.

What you mean is "cranks but won't start/run".

As above--fuel pressure test.

One wonders if your gas tank has been vandalized, maybe the new filter is contaminated already. (Probably not.)

A scan tool could be helpful. I'd be looking for an RPM signal from the crank sensor as the key is turned to "crank" and the starter motor runs.

 

[8thNote]

"Cranking" and "turning over" are the same thing.

What you mean is "cranks but won't start/run".

As above--fuel pressure test.

One wonders if your gas tank has been vandalized, maybe the new filter is contaminated already. (Probably not.)

A scan tool could be helpful. I'd be looking for an RPM signal from the crank sensor as the key is turned to "crank" and the starter motor runs.

I have an Innova 5412 code reader, I'll hook it up asap. I'm in the middle of a front end job on the wife's Subaru, so that takes priority right now. I'll get to the Burb after I finish wife's car, since the Burb is "just a toy"

 

[Pinger]

I had similar symptoms to yours with my Suburban. I was reasonably confident that the fuel pump was OK as the previous owner had replaced it but had erratic fuel pressure at the test port - sometimes the spurt, other times nothing. Sorted out the connections at the fuel pump pigtail (nasty crimps) and it's all good. The pigtail sits on top of the tank and is accessible (just!) from the front of the tank.
I wouldn't get too hung up about fuel pressure right now. Keep looking at the test port. My guess is at some point fuel will be absent. It'll be worth checking the fuel pump relay also (it can be bridged).
If none of the above, then interrogate pressure as suggested by others.

 

[8thNote]

I had similar symptoms to yours with my Suburban. I was reasonably confident that the fuel pump was OK as the previous owner had replaced it but had erratic fuel pressure at the test port - sometimes the spurt, other times nothing. Sorted out the connections at the fuel pump pigtail (nasty crimps) and it's all good. The pigtail sits on top of the tank and is accessible (just!) from the front of the tank.
I wouldn't get too hung up about fuel pressure right now. Keep looking at the test port. My guess is at some point fuel will be absent. It'll be worth checking the fuel pump relay also (it can be bridged).
If none of the above, then interrogate pressure as suggested by others.

Thanks for the tip. Much appreciated

I still haven't had time to investigate further, the Suburban is just sitiing in the driveway looking forlorned. But I will update this thread as I go

 

[8thNote]

So I finally got the time/motivation to do some investigating on the Suburban. I bought a harbor freight fuel pressure test gauge. I hooked it up to the test port, and there is 0 psi with the key in run position and while cranking. Crap. Also, no sound from fuel pump when key is turned to run position (I understand that it should come on for 2 sec to prime the system).

Fuel pump fuse is good. I bought a new fuel pump relay (previous owner had put a 4 pin relay instead of the correct 5 pin). I also tested the relay pin terminals in the power block under the hood with test light and/or multimeter. They all had correct voltage at correct time or grounded correctly (as the case may be, depending on the terminal).

Also tested wires at the fuel pump connector harness. They were all getting power and ground was good.

Codes that are showing are p0102, p0340, and p0441. They are, I believe, unrelated to the lack of fuel pressure. I will address them at a later time.

I guess all this means the pump is fried. Unless anyone has any other suggestions ??

 

[HotWheelsBurban]

So I finally got the time/motivation to do some investigating on the Suburban. I bought a harbor freight fuel pressure test gauge. I hooked it up to the test port, and there is 0 psi with the key in run position and while cranking. Crap. Also, no sound from fuel pump when key is turned to run position (I understand that it should come on for 2 sec to prime the system).

Fuel pump fuse is good. I bought a new fuel pump relay (previous owner had put a 4 pin relay instead of the correct 5 pin). I also tested the relay pin terminals in the power block under the hood with test light and/or multimeter. They all had correct voltage at correct time or grounded correctly (as the case may be, depending on the terminal).

Also tested wires at the fuel pump connector harness. They were all getting power and ground was good.

Codes that are showing are p0102, p0340, and p0441. They are, I believe, unrelated to the lack of fuel pressure. I will address them at a later time.

I guess all this means the pump is fried. Unless anyone has any other suggestions ??

Could be like @Pinger suggested, that the pigtails are messed up on the pump harness. You may be able to get it out without dropping the tank. We could not on our job, couldn't even see them till the tank was partway down. The original harness turned out to be okay, we just had to cut the old connection off and splice the new one in.
I had looked at everything besides the pump, hoping it wouldn't be that. But it was.