Idles high when cold...

[Buzzman]

Hey there,

Tackling things one at a time here with my new '79. Next up is the high idle problem I'm having when the motor's cold. Every morning when I go start up the truck and let it warm up a little, it idles way too high - I'm guessing 1500rms or so. All the way to work I barely have to give it any gas, it just gets up and goes on it's own. And when I turn it off, it diesels for a few seconds and sputters out. Now, when I start it up for lunch, it's usually fine, and idles normal. The rest of the day is fine as well.

I've done a little research around here, but most of the threads seem to be dealing with a constant high idle, whereas mine settles down as the day goes on.

So I know I need to be mindful of vacuum leaks, but because of the dieseling and eventual leveling out, it must be the carb. Could the butterfly valves stick open when cold, letting too much fuel in and causing the dieseling? Or is the problem with the fast idle cam? The only reason I don't think it's the fast idle is because it seem like that would cause it to run high all day.

If it is the butterflies, any tips? Thanks!