2000 GMC Sierra 1500 Flood vehicle wont idle

[JReed]

Hello I am having an issue keeping my truck idling on its own. Here is the history on the truck. 2000 GMC Sierra 1500 4.8L automatic with manual 4x4. Bought from auction as a flood vehicle. Water was in the engine in the oil and in the cylinders. Got that all out and new plugs, wires, new fuel, oil and filter. The truck runs now but it will not idle on its own. If you give it just a slight amount of throttle it will run. If you let off the gas it dies. I checked the throttle body and cleaned it. Clean air filter. The fuel pump primes 50psi but I haven't checked it while running. Any thoughts as to why it wont idle on its own? It will rev all the way to redline and you can drive it around a little if you two foot it. The engine sounds healthy but wont stay running.

Edited February 13, 2019 by JReed

[sefiroxx]

Verify
- each cylinder is firing
- each injector is opening
- each O2 sensor is cycling
- Fuel Trim are varying

While checking the last two, use a scanner to verify proper readings for other sensors like TPS, temp etc

After above, then IAC might need replacement.

(PS Tranny fluid might need to changed as well)

[carnau]

10 hours ago, JReed said:

Hello I am having an issue keeping my truck idling on its own. Here is the history on the truck. 2000 GMC Sierra 1500 4.8L automatic with manual 4x4. Bought from auction as a flood vehicle. Water was in the engine in the oil and in the cylinders. Got that all out and new plugs, wires, new fuel, oil and filter. The truck runs now but it will not idle on its own. If you give it just a slight amount of throttle it will run. If you let off the gas it dies. I checked the throttle body and cleaned it. Clean air filter. The fuel pump primes 50psi but I haven't checked it while running. Any thoughts as to why it wont idle on its own? It will rev all the way to redline and you can drive it around a little if you two foot it. The engine sounds healthy but wont stay running.

Drive by cable or drive by wire?

 

If it is drive by cable, you need to adjust the throttle blade lever. Some times on older vehicles they tend to bend a little. If you look at the underneath of where the cable connector is, it will be a small t10 screw. Turn in 1/4 a turn at a time until the idle is right. 

[JReed]

12 hours ago, carnau said:

Drive by cable or drive by wire?

 

If it is drive by cable, you need to adjust the throttle blade lever. Some times on older vehicles they tend to bend a little. If you look at the underneath of where the cable connector is, it will be a small t10 screw. Turn in 1/4 a turn at a time until the idle is right. 

It is drive by cable and that actually fixed it I think. I adjusted it and it now idles on its own. Thanks for the help. It did end up using a T15 screw though. Haha

[carnau]

On 2/14/2019 at 8:35 AM, JReed said:

It is drive by cable and that actually fixed it I think. I adjusted it and it now idles on its own. Thanks for the help. It did end up using a T15 screw though. Haha

Great! Glad it got fixed! Check out my youtube channel and subscribe. I'm posting self help videos on your type vehicle all the time. www.youtube.com/cdarnau