99 Suburban fires and dies

[Slickbod]

Hello.

I replaced a failed power window motor in the driver's door of my 99 Suburban. When I reconnected the battery, the vehicle would fire a few times and die, like it is getting an initial shot of fuel and then is cut off.

I have had this problem before several times. It would eventually start after a lot of tries. My mechanic replaced the fuel pump the first couple of times I had it in the shop. After the second time, it wouldn't start right after the fuel pump was replaced. At the time, I thought it was the ethanol fuel. I switched to regular unleaded and it ran fine for some time. Then one day, I backed my boat into the water, and the Sub wouldn't start on the ramp. We stumbled on the fix - opening the gas cap. I replaced the gas cap and it has run fine until today.

It has new plugs, wires, distributor and cap.

The sub has 174,000 miles and is the 5.7 V-8.

Thanks for your help.
Slickbod

[Q-Bert]

run a fuel pressure test
vortecs require high pressure ~60-66psi IIRC.
The following is a quote that I see MT-2500 always make when fuel pressure is suspected. I'd imagine he has it handy to cut and paste every time.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

Don't use airtex pumps. I've heard they are crap. Stick with the ac/delco.

[Slickbod]

Thanks Q-Bert

I found the problem. The security system needed to go through the 10 minute cycle, but it was a little different than the book told me. It said the security light would flash if it was going to cut off the fuel. If it is a solid light, the system is just not active. Well, the light never flashed, but it stayed on solid. The first time I left the key on for 10+ minutes, and the security light stayed on and it wouldn't start. I unhooked the battery, reconnected it, and left the key on for 10+ minutes and this time the light went out. The Sub started and ran right away.
I put 120 miles on it yesterday and about 80 miles today - it ran fine.

Regards,
Slickbod

[MT-2500]

Glad you got it going.
Some times you have to do the key on off things 3 times in a row with key on 10 minutes untill the light goes off.
Good Luck

[Slickbod]

Thanks for the additional tip MT-2500.

Regards,
Slickbod