So does anyone else's truck stay in high idle for long periods of time? My truck is an 85 and it has been warm here so there is no need for it to stay idling high as long as it has. It usually stays around 1100rpm. Then when it gets warm it will go down to 7 or 800rpm. If you tap the throttle fast to see if it will go down it doesn't change. Any ideas? Also what is the knob with a vaccuum line going to it on the passenger fender?
Ok the thing on the inner fender is a vacuum switching valve. Part#17650 in the pic lower left. By the way I am a Gm parts guy but we have a old Toyota Catalog in the back. Dang phone will only load the pic sideways.
my 85 has done that for years. From what I have read it is probably an old cracked diaphram that is supposed to actuate the cold start linkage on the carb as the engine warms up. I have been doing this by hand whenever I have to start the engine if it hasn't been running recently. You have to reach under the air filter to mess with that linkage. Haven't looked into fixing it much as I am planning an engine swap and don't drive the truck often.
