Chev 5.3 crank/no start

[KevinB]

Hopefully someone out there can confirm this before I do the work

I got a '01 Tahoe with a 5.3. Drove it last weekend...everything was fine. Go to drive it last night and it's running very bad. I thought at first it was just a mis-fire, possible bad coil. Go out this morning to fire it up and runs even worse...will not even rev past 2K. A minute later it will not even start. Putting a fuel pressure gauge on it shows 55lbs. Using starting fluid, it will start and rev to whatever you want it to, then it will die after the ether runs out.

I'm thinking fuel pump, but why would it have pressure and fuel at the rail (fuel comes out of the gauge when you release the pressure.)

TIA!

 

[Quick6'n'-K.C.]

Water in fuel..


Thats seems to be happening more and more lately.
We popped the schrader out, put a hose on the schrader and let the car run while it was draining into a bucket. This was on a ford, but you get the idea.

Drain the fuel out and replace it with fresh good gas

BW

 

[TURBOTWIN2]

Pull the hose off of the fuel presuure regulator and see what happens. Seems to me the pressure spec is 60-65 psi, but I could be wrong. I'd physically remove the filter and see if it's clogged up, if you can't blow through it easily, replace it. That may be your problem or the root cause of everthing, making the fuel pump overwork.
You can have pressure but insufficient volume to run correctly. HTH.

 

[KevinB]

Water in fuel..


Thats seems to be happening more and more lately.
We popped the schrader out, put a hose on the schrader and let the car run while it was draining into a bucket. This was on a ford, but you get the idea.

Drain the fuel out and replace it with fresh good gas

BW

I got the tank out. The fuel has a white tint to it I think you might be on to something. I put a fresh Walbro pump in that I had on the shelf and it's still not starting? Fuel filter was not clogged but not exactly the easiest to blow through. Headed to the store now to get a filter. I am going to put some fresh gas in a bucket and drop the pump in there to see if it starts. I have not put the tank bank in the vehicle yet.

 

[KevinB]

Also, I got a ton of fuel coming out of the gauge's pressure relief valve, so I'm pretty sure volume is not the issue anymore.

 

[Quick6'n'-K.C.]

Id try that, you might just be out a tank of gas, and reuse the factory pump.

Id clean that new walboro up and cycle some good fuel through it and put it in a sealed plastic baggie so it doesnt dry out.

Good luck, white fuel cant be good for it.

BW

 

[Chuck Leeper]

The LS based engines run at 58psi. [4 bars]
Could have eaten the crank or cam sensor.
Crank sensor is at the starter area, in the side of the block. The cam sensor is at the rear of the intake manifold, in the block.
Time for a scanner.

 

[KevinB]

I got it running but seems to have a slight miss. It runs good enough to drive to the nearest Autozone to get some readings. The SES light is on.

 

[KevinB]

I also drained the tank 100% and put fresh gas in. Getting ready to dirve it now and get the codes checked out now.

 

[TURBOTWIN2]

Let us know how it does. I saw specs online of 55-62 psi fuel pressure. You might want to take a sample of your old gas and see if it separates into water and gas after sitting a while.

 

[KevinB]

Are those numbers with the vacuum line off?

Anyways, the miss cleared up after a 1/2 mile of driving. It runs perfect:biggrin:

It was either the pump or bad gas. I got the old gas in a few jugs, one of which is clear so I will be able to see what happens to it in a few days. I left the Walbro in it b/c the vehicle has over 100K and it had the original pump.

It pretty much consumed my Sunday but didn't cost me a dime and my tow vehicle is back up and running

Thanks everyone and thanks to D-Day for taking my call on a Sunday...See you at BPG