I have a 1986 F-250 6.9L that is having idle issues. I was driving it when it started revving up and wouldn't drop down to a regular idle. It was revving up so high that in fourth gear it would start to shake. I thought the problem was a bad Idle Solenoid so i bought a used one from Ebay and today put it on. However it is having the exact same issues as before where when you rev it up it will stay at a elevated idle and it doesn't matter if the electrical connection on the solenoid is connected or not. Any help would be much appreciated as I'm new to diesel vehicles.

 

unhook your thottle cable from the injection pump and see if it binds. they normally break the plastic guide near the injection pump and get hung up.

 

If its the idle solenoid u can disconect

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Its not the throttle cable. The problem is when you give it gas it will stay at a higher rev for a couple seconds and then drop back down to a regular. And im just tapping the accelerator. Also it does this with the idle solenoid connected and disconnected, it dosnt matter. If the idle solenoid is connected the little piston on it will not push back in all the way by itself. You can manually push it back in but as soon as you give it gas again it pushes out and wont come back all the way.

 

Alright i think i found the problem. There is a Temperature Switch that sends power to the Idle Solenoid when your engine is cold. Sometimes the Switch gets messed up and will continuously send power causing the idle problem i have been having. Going to pick one up tomorrow and try it, well see what happens.

 

Not a lot of luck with the temperature switch. Kinda stumped at the moment. Herd also could possibly be the injector pump, but out of cash right now so the truck will have to wait.

 

Had the same problem with mine. Look at where the cable is attached to the gas pedel. See if it sticks when you press it. My mechanic replaced the throttle cable and all is fine now.

 

like crawler said man, that too is where mine went bad, plastic inside the spring at the ip end of the cable,