My van has the heated controlled choke that will idle down when it is in park and warmed up. However, when I drive the van for a short time it revs back up and won’t come back down. This is a gas carb. system. Is it the choke thermostat or could it be something else? I can be emailed at firstname.lastname@example.org with an answer or thought. Thanks!
It’s unlikely to be the choke thermostat. That’s a simple bimetallic spring that once “unwound” due to heat won’t rewind until it cools.
You need to have someone look at it that knows carbs. It may be as simple a throttle linkage that’s hanging up when it gets heated or be something more sinister like a sticky float that’s not regulating the pressure in the float bowl properly.
The chokes are basically simple, a bimetal strip controls the choke plate. And attached to it is a round piece with steps. When closed the idle screw touches the highest step, and as the car warms up, the plate rotates and the idle screw touches the lower steps. When fully warmed up the screw is touching either the smallest plate or another piece.
The problem might be something as simple as the choke not opening all the way or a bit too far and causing the throttle to touch something it shouldn’t. One thing with older vehicles is that you need to help the choke finish opening. Just a quick snap of the throttle does it. If that doesn’t drop the idle back to normal then you need to check the choke and idle adjustments.
the steps you speak of are part of the fast idle cam.
too much to explain here,without prior experience just be spitting in the wind,plese dont be offended.
too much to explain on the net,must be seen