extremely high idle 87 B2000.

so yeah, my truck is idling at wot it seems..my truck does not have a tach, but its obviously idling high. the emissions stuff has been removed, and i ran it without that for about a week. it rained the last few days and when i went to start it, extremely high idle. also, adjusting the screw on the carb doesnt seem to do anything unless i turn it clockwise enough, then the rpms climb some more -_-

i should also state it ran fine until today.

Stock carb or Weber? I'd first make sure that the throttle return spring hasn't broken (mine has broken a few times) or is weak so it doesn't fully close.

Also make sure that the accelerator cable isn't binding somewhere, and that throttle cam on the carb will move back to idle if you presson it with you hand

its a stock carb. the throttle linkage is fine, and the return spring is new, still fine. i rebuilt the emissions and re-installed it, but that made no difference. i even disconnected the ecm and it ran the same. could it be the choke? also what is the throttle cam look like? im a carb newb.

I would remove the return spring or see if you can push the throttle back. Another possibility is that you have a improper seal on the carb where it bolts to the intake manifold and its sucking in more air and trowing off the air fuel ratio. To test that take some carb cleaner and spray around the base of the carb where it meets the manifold, if you notice a change in rpm you have a leak. To fix this you may need to replace the gaskets which I believe there are two of them they are 2 bucks a piece at your local auto parts store. Hope this helps.

i tried the carb cleaner trick and the rpms did not change from what i could hear. a vacuum line going from a sensor on the front of the intake came loose and my rpms dropped some..hooked it back up and they climbed again. since its not hard to find a vacuum diagram for the truck, im going to pull them all off and replace them, and let the carb soak in some cleaner. the truck did sit for 2 years before the previous owner decided to get it running and sell it.

I had a similar problem with my old carb so I got one off a guy from Craigs List for $25 replaced both gaskets and it fixed the problem but i also have all my emissions hooked up. Over time the fuel and heat just wore out those gaskets. You know they are cheap and the carb is only 4 nuts takes very little time to replace. I mean I was idling at 2000 rpm constantly until I replaced the carb and gaskets found out that my butterfly valves where getting hung up and wasn't sealing up letting in more air then fuel, and that one of my gaskets was leaking and when taking it apart they just crumbled away.

I had to edit my self the spring part I got backwards if its too weak it wont pull it back meaning you need to go to a stiffer spring but if you go to stiff it will making it harder to press the gas peddle. To fix that you need to stretch the spring. Had one of my dyslexic moments I apologize. any how make sure the throttle is closing.

Another thing you can check is to make sure the choke is opening all the way. If it is sticking the engine will rev too high. There is a screw adjustment behind the main carburetor kind of hard to find that you can loosen up so it comes off the cam it hits. But I am guessing that maybe the choke unloader has quit working and maybe that allows the choke plate to stay closed partially.

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As you can see from the picture this is an example of what gets done to these factory carburetors.

The screw under the choke adjusts high speed idle and if it's too tight it won't let the cam loose and that can cause a high idle.