Idle speed too high

[Dan]

How do I correct too high of an idle speed? The rig cruises around at about 25mph with my foot off the gas! Timing seems ok, but I'll be checking it to make sure. Choke appears to be working properly - opens and closes when it is supposed to. Linkage doesn't appear to be sticking anyhwere. When the car was warm, I backed out the idle screw all the way until it stops touching the linkage, but it's still way too high. Any suggestions?

It also diesels when I turn off the ignition, and I'm assuming that this is the reason why.

[ September 16, 2001: Message edited by: Dan ]

[Dexter Shark]

Mine does the same thing, don't know how to fix it though.

[Dan]

Would a vacuum leak cause this?

[okidoc]

Have you adjusted the mixture screws on the front of the carb (if it's a 2150)? If there is a vacuum leak these may be adjusted out to compensate w/ higher RPM. Best way to find a vacuum leak is with carb cleaner. Spray it around the carb and top of the engine if it hits a vacuum leak the engine wil gain about 500-700 rpm pretty much instantly, since have now isolated the source you can "hopefully" repair it.

[Michael]

Does it keep running after you turn your key off. How does it idle with it in park? If your answer is yes and really high then you need to adjust the idle screw at the back of the carb... If it is a 2150 anyway. I had the same problem.. If it is now then you should get that carb cleaner and spray around the base of the carb. More than likely the gasket and the sorry spacer is blown out. Or you have a vaccum leak somewhere else causing it to take in a lot of air. :eek:

[wagdriver]

There are two things to do to set the idle speed correctly on our beasts.
1) disconnect the wire going to the soleniod on the carb.
2) put the vehicle in neutral and adjust the idle with screw next to the carb base to 500rpms.(base idle)
3) reconnect the solenoid.
4) blip the throttle to let the solenoid extend.
5) put the vehicle in drive with the wheels blocked.
6) adjust the idle speed with the adjuster on the solenoid to a speed of 600rpms(curb idle) may have to be a little higher with A/C.
These adjustments have a tolerance of +/- 50rpms by the book. Check all the items the previous posters have presented. Good Luck!
My 88 is set up this way and it is just fine. smile.gif

[WillyPete]

could be a sticky throttle linkage. in that case you might have to replace the accelerator cable.

in my case, my fast idle was due to the no. 8 plug wire being laid across the carb, blocking the linkage from closing completely.

it's always the little things...

[Dan]

okidoc - I'll check for vacuum leaks today. The idle mixture screws - do you adjust both of them the same amount?

michael - Yes it runs after turning it off, that's what I meant when I said it "diesels". The idle screw on the back is adjusted all the way out, so I guess I'll check for vacuum leaks.

wagdriver - thanks for the instructions. I'm not sure if it will adjust any lower but I'll try this out.

willypete - there doesn't seem to be any linkage sticking anywhere, I wish though!!

Thanks all for the help. I'll check on the vacuum leak and see what I come up with. The vacuum lines are pretty suspect, and it's hard to say if there is any thing leaking out of the carb gaskets.

[porchpiggy]

Did it just start doing this on it's own? or was it after you worked on something? :confused: Mine was too high because I set the cable distance (while installing a 1406) while the carb was "choke closed/fast idle, so I did not have the right slack in the cable.

[ September 17, 2001: Message edited by: porchpiggy ]

[Dan]

I just bought the rig and it was that way when I bought it. I initially thought it was just the choke not working properly and an easy adjustment. Accelerator cable has plenty of slack when at idle - good thought though. I probably won't get a chance to work on it until this weekend, so all of these suggestions are helpful. Thanks!

[<SAR-4800>]

Dan,
My '88 GW does the exact same thing.

If I rev the engine (while in park)... and I mean really rev it, it will settle back down to a much lower idle for the rest of the time it's running.

I just changed out my plugs and found the old ones had a hellacious carbon build-up on them, causing carbon glow. I haven't had it continue to run after shutting it down yet, but I've only driven it once since I changed out the plugs.

Also, the idle screw on the 1406 was set way too high... going from park to drive with the RPM at around 2000 was being rough on the tranny.

[denaliak02]

Dan,
1)how well does it start when warm? is it slow turning? i suspected the timing being too high when you said it diesels.
2) did you buy it locally? (is it adjusted for different elevation)
3) do you know of any timing chain/dist. work done to the rig before you got ahold of it?

just some ideas...

[Jowersgd]

The most likely cause of your problem is that your fast idle is stuck. Same thing was going on with mine when I first got it. The problem is that it is not kicking down when you hit the accelerator like it's supposed to. It's either stuck or it's set improperly. You can set the fast idle by taking off the air cleaner, pull back the throttle, and while it's back close the choke completely, then let go of the throttle and then the choke. The fast idle is now set. Start the jeep. Then hit the accellerator. If the idle doesn't drop you know what the problem is.

[reddog]

Wagdriver and Jowersgd gave good info. If your high idle cam is not stuck (open the throttle and then back off the high idle cam by hand and then start it without touching the throttle) then it sounds like your solenoid isn't adjusted properly