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Very high (5k rpm) idle on start up

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Old 11-13-2015, 08:16 PM
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Very high (5k rpm) idle on start up

What's up guys, I'm new to the forum and new to these yotas. I bought an 87 for a daily driver and then 3 days later happened to buy an 85 from my uncle. Both trucks have the 22r.
I have googled this issue and found some info on the 22re. But these guys are saying 1500-2k is high. On a cold start my 87 when jump straight to 5k and I can tap the gas and get it to drop to 3k but it sits there. To test it once I just start driving lightly and every time I shift jumps back up. Once it's warm 7-800rpm all day no issues. Never had this problem in the first few days until I changed the plugs. Had motocraft plugs in it... Some people. So I put new ngks in and first thing started it and the rpms shot up. Any help is appreciated. Give me some things to look for and I'm sure u guys can help me solve the issue! I know a ton about hondas but never messed with these yotas. I'm confident with a little advice I can get this thing fixed. Thanks!
Old 11-14-2015, 05:08 AM
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On the backside of the carb is where the high idle assembly is. There's a screw back there that control's how much the stepped high-idle cam will open the primary throttle plate.k The fast idle screw is a flathead one kind of facing downward towards the passenger wheel.

The choke being set is what pulls the high idle cam into position. It is also why you have to pump the gas before you start, so the plate will open enough for the fast idle cam to drop into place.

Last edited by mct75; 11-14-2015 at 05:09 AM.
Old 11-14-2015, 07:57 AM
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Originally Posted by mct75
On the backside of the carb is where the high idle assembly is. There's a screw back there that control's how much the stepped high-idle cam will open the primary throttle plate.k The fast idle screw is a flathead one kind of facing downward towards the passenger wheel.

The choke being set is what pulls the high idle cam into position. It is also why you have to pump the gas before you start, so the plate will open enough for the fast idle cam to drop into place.
Okay I will check that out when I'm off work. Only reason I find something weird is because before I changed the spark plugs I had no issues... On another hand I opened the hood this morning and noticed my upper radiator hose was collapsed. Hmmmm could be my issue or not helping as I have read no coolant flow will make it idle higher. I'll start first with the radiator cap. I haven't been driving it the past days but I'm check some stuff out after I'm off. Thanks for the help! I'll post an outcome.
Old 11-14-2015, 10:02 AM
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I would have to imagine spark plugs to have nothing to do with idle (unless maybe it was missing until it warms up). I can see the coolant having a slight impact just due to the water pump stalling out, but I'd expect it would be hard to measure.

Maybe an expert will chime in!
Old 11-16-2015, 12:31 AM
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Cold start high idle/ narrowed down to carb issue

Okay guys I've narrowed this down to a carb issue. I've never messed with carburetors before. I figured this out by comparing both of my trucks. Both trucks have weber carbs. The problem I am having is the linkage isn't hitting the fast idle screw after a decent rev/ movement of the gas pedal. There is plenty of slack in the throttle cable. If I open the butterfly's fully open by hand then open the throttle all the way it will return to the fast idle screw after I let off the throttle and idle at a normal rpm. If I close the butterfly's then open the throttle it goes back to not touching the idle screw hints the instant revving up if the motor is running. I tried letting the truck idle and while being revved sprayed carb cleaner all over the linkage and inside the carb. And info as to why this is happening would be great. Any suggestions let me know and I'll will try anything im informed of! Sorry for the long post, I want to give as much info as I could. Here is a pic of where the linkage is stopping without manually opening the butterfly's first to purposely let it return to the screw in this scenario. It's a 32/36 with electric choke if that makes a difference. Thanks!


Last edited by Zpayne21; 11-16-2015 at 12:42 AM. Reason: Picture
Old 11-16-2015, 04:12 AM
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I have heard that there's some nut on the weber's throttle arm that can be loosened if the throttle is "sticking" open. I don't have one so that's all I know.
Old 11-16-2015, 09:19 AM
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Originally Posted by mct75
I have heard that there's some nut on the weber's throttle arm that can be loosened if the throttle is "sticking" open. I don't have one so that's all I know.
I'm going to do a search on that. Thanks for ur help man I appreciate it!
Old 11-16-2015, 02:35 PM
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I took a bunch of slack out of the throttle cable and had to back the screw out behind the electric choke all the way. There is some sort of mechanism that was catching on the screw which wasn't letting the throttle return to the fast idle screw. Correct me if I'm wrong but I'm pretty sure that screw adjust how high it idles on a cold start with the choke engaged? Here is a pic of the screw I had to back out. As far as how to set it or what needs to be done now is what I do not know.

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