1999 Suburban 4x4 With A 5.7...starts But Then Dies Right Out

ShortyYFZ450R · April 13, 2009

This has happend on 3 different occasions, out of nowhere it just won't start and then if I wait a couple days it will start up & run fine for a couple weeks or a month & then do it again. This time it hasn't started though...I've checked the compression, it's 150. I checked the spark, it's firing. I checked the fuel pressure, it goes up to 61 & then drops right down to 56 & holds there steady. It will start but then dies right out. If you spray carb cleaner in the throttle body, it will stay running but it's pretty rough. I put a new fuel pump & fuel fliter on it 14 months ago and I put all new cap, rotor button, spark plugs & wires on it 3 months ago. It had a code back then that said cylinders 2 & 8 were misfiring but when I tuned it up that fixed that problem. I had a friend come over and the only code showing up now is the oxygen sensor, he cleared the codes and now it won't run long enough for any codes to show up.

Thanks! Any help will be appreciated!

ShortyYFZ450R · April 13, 2009

This has happend on 3 different occasions, out of nowhere it just won't start and then if I wait a couple days it will start up & run fine for a couple weeks or a month & then do it again. This time it hasn't started though...I've checked the compression, it's 150. I checked the spark, it's firing. I checked the fuel pressure, it goes up to 61 & then drops right down to 56 & holds there steady. It will start but then dies right out. If you spray carb cleaner in the throttle body, it will stay running but it's pretty rough. I put a new fuel pump & fuel fliter on it 14 months ago and I put all new cap, rotor button, spark plugs & wires on it 3 months ago. It had a code back then that said cylinders 2 & 8 were misfiring but when I tuned it up that fixed that problem. I had a friend come over and the only code showing up now is the oxygen sensor, he cleared the codes and now it won't run long enough for any codes to show up.

Thanks! Any help will be appreciated!

What is the code definition? If it is for either bank sensor 1 it could cause your problem....

I had a similar problem and found a pinched wire under my fuse box, not to say its gonna be the same on yours but very easy to check, pull the fuse block assy up and have a peek.

The one code (PO107: Manifold Absolute Pressure/Barometric Pressure Circuit Low Input) was because it was unplugged. I plugged it back in & now it's fine...I also read somewhere that it was supposed to have 5 volts input, so I checked it & it does.

The other one (PO161: 02 Sensor Heater Circuit-Bank 2 Sensor 2)

I have talked to a couple mechanics, 1 said it's the modular under the distributor cap..another said it's the fuel pressure regulator under the intake.

Thanks for the help!

ShortyYFZ450R · April 13, 2009

I've read that oxygen sensors should be replaced as a regular maintenance item every 60,000 miles. They seem to get filled with all that nasty stuff in the exhaust and then don't work like they should.

Also might want to check your Idle Air Control Valve for proper operation (read factory maintenance manual for diagnosis and testing). And other things which have to do with idle.

Yea if the sensor is bad, it causes the vehicle to get poor gas mileage. If the air control valve is bad will it cause the truck to not start at all?

bill190 · April 14, 2009

Funny thing happened today, not long after I posted the above about the Idle Air Valve, I went to work on a truck with a check engine light on, and guess what?

It had an Idle Air Control Valve code! And that was all.

I said; hummm... I was just talking about that valve on the internet.

bill190 · April 13, 2009

Well I imagine it would still start if everything else is working as it should, but maybe if other things are marginal, then? (Like oxygen sensor(s), PCV system, or other...)

Anyway it seems to me if it is getting fuel and spark, then checking the air system would be a good idea.

L29er · April 13, 2009

This has happend on 3 different occasions, out of nowhere it just won't start and then if I wait a couple days it will start up & run fine for a couple weeks or a month & then do it again. This time it hasn't started though...I've checked the compression, it's 150. I checked the spark, it's firing. I checked the fuel pressure, it goes up to 61 & then drops right down to 56 & holds there steady. It will start but then dies right out. If you spray carb cleaner in the throttle body, it will stay running but it's pretty rough. I put a new fuel pump & fuel fliter on it 14 months ago and I put all new cap, rotor button, spark plugs & wires on it 3 months ago. It had a code back then that said cylinders 2 & 8 were misfiring but when I tuned it up that fixed that problem. I had a friend come over and the only code showing up now is the oxygen sensor, he cleared the codes and now it won't run long enough for any codes to show up.

Thanks! Any help will be appreciated!

What is the code definition? If it is for either bank sensor 1 it could cause your problem....

I had a similar problem and found a pinched wire under my fuse box, not to say its gonna be the same on yours but very easy to check, pull the fuse block assy up and have a peek.

ShortyYFZ450R · April 15, 2009

Funny thing happened today, not long after I posted the above about the Idle Air Valve, I went to work on a truck with a check engine light on, and guess what?

It had an Idle Air Control Valve code! And that was all.

I said; hummm... I was just talking about that valve on the internet.

That's crazy! I figured out what it was!

I did some research online and found out about the passlock system. If the security light is on it will not allow fuel to go to the engine. Our security light was on so I did some checking in the truck. There was a wire in the steering column that was broke! I guess it is a common thing in those trucks. So I replaced the wire & the light went off...now the truck is fine!

bill190 · April 13, 2009

I've read that oxygen sensors should be replaced as a regular maintenance item every 60,000 miles. They seem to get filled with all that nasty stuff in the exhaust and then don't work like they should.

Also might want to check your Idle Air Control Valve for proper operation (read factory maintenance manual for diagnosis and testing). And other things which have to do with idle.