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Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

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post #1 of (permalink) Old 08-10-2004, 10:00 AM Thread Starter
 
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Carb Gurus Help Again

Background..... here is what I've got now... a 1989 258 with automatic and an original model Carter carb, most of my emmision stuff removed and plugged and was running pretty well til a few months ago.

Here's what I'm not doing..... I'm too cheap to buy the Weber and the Motorcraft 2100s I've found aren't worth rebuilding... its a VERY popular carb here on the coast.

Heres what I've done..... a buddy gave me a matching Carter to rebuild and see if that fixed my idle problems. I went through the carb very carefully and made sure I got it set-up exactly according to the specs provided. Turns out the idle cylinoid on the rebuilt carb was bad, the jeep would run but could not idle at all... just shut down without a lot of gas. Swapped the cylinoid off the original carb, now it runs. It runs great at anything over idle (accelerates, has power, no hesitation) but as soon as you take the foot off the accelerator, its starts to sputter like before. It doesn't kill until I apply the brakes however (stop signs, shifting automatic out of park, etc). I've adjusted the idle set screw on the side of the carb to increase the RPMs a little and it idles fine at 1000 rpm, apply the brake to shift into gear and it drops to 500 or less... sputters and kills.

What is going on? Vacuum? I now have two Carters which seem to be doing the same thing one rebuilt, one not.... therefore, its not likely the carb? UGH!!! Some help other than "Buy a weber" would be appreciated.


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post #2 of (permalink) Old 08-10-2004, 10:45 AM
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Re: Carb Gurus Help Again

sounds to me likeyou may have a vacuum issue. Try unplugging the vaccum line from your brake booster, pluggin it and and then apply the brakes to see if the idle still drops, maybe your not developing enough vacuum and when you apply the brakes its pulling down your carb????? just a guess
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post #3 of (permalink) Old 08-10-2004, 11:31 AM
 
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Re: Carb Gurus Help Again

I had the same problem on a CJ...it was the brake booster...
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post #4 of (permalink) Old 08-10-2004, 12:04 PM Thread Starter
 
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Re: Carb Gurus Help Again

I'll try that over lunch. If thats the problem is it the booster itself or the vacuum system, ie, which would I end up replacing? Would the brakes feel a little soft if the booster was going bad or not enough vacuum? I'm not exactly sure how this part works.

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post #5 of (permalink) Old 08-10-2004, 04:10 PM Thread Starter
 
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Re: Carb Gurus Help Again

Nope, I took the vacuum off the booster and it didn't make a bit of difference. It still seems to sputter when the brake is applied. Things that make you go HUMMMMM. So far I'm only out the one rebuild kit... any other thoughts?

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post #6 of (permalink) Old 08-10-2004, 05:03 PM Thread Starter
 
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Re: Carb Gurus Help Again

New thought:

My brother-in-law thinks now it sounds like it could be the torque converter. If its sticking and not coming off when I brake it could be the problem. We are not sure if this would be the case or not. Any thoughts?

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post #7 of (permalink) Old 08-10-2004, 05:55 PM
 
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Re: Carb Gurus Help Again

I think it would shimmy like heck if it was the TC...

Did you plug all the vacuum stuff when you removed the brake booster?

Still sounds like a vac leak to me...
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post #8 of (permalink) Old 08-10-2004, 06:08 PM
 
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Re: Carb Gurus Help Again

Is this brought on by applying the brakes at idle (standing still, transmission in neutral or park), in which case I would say it is a vacuum leak. You could further confirm this by pinching the vacuum line with some vice grips to see if it cures the problem.

If it only occurs while in motion, the problem could be due to the effect of enertia on the fuel. If the float level is unusually low or there is dirt in the bowl, hard braking could reduce fuel flow to the idle circuit.
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post #9 of (permalink) Old 08-11-2004, 10:50 AM Thread Starter
 
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Re: Carb Gurus Help Again

It seems to be less noticeable in Park and Nuetral. In fact if I take it out of gear at an intersection, it seems to idle up again. Still sputters just not as bad. Is there another circuit that pulls vacuum at a stop or when braking. I noticed no difference when I pulled off the booster other then I could hardly stop.
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post #10 of (permalink) Old 08-11-2004, 12:04 PM
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Re: Carb Gurus Help Again

Since I'm not intimate with your system I'll have to shoot in the dark.
The idle solenoid -- what activates it? When is 12 volts applied to it? I assume it's anytime the key's in the ON position? Anything loose in that connection slams it shut, killing the engine - or is supposed to.
Adjustment for that - start engine, disconnect the wire to it - adjust the stop screw so it barely idles.
Connect the wire - rev it up so the solenoid extends, now set your normal curb idle - 650 - 750 - whatever you like.
Now that that's done check for vacuum leaks, spray a BURNABLE carb cleaner around looking for an idle R's change.
Caution - most carb cleaners don't burn like gas - you can be misled. Gumout works OK.
Are there any other "vacuum" devices" still being used - smog or otherwise - gulp valve etc? Sometimes a slight miswiring of vacuum lines can drive ya nuts!!!

That solenoid helps keep it from dieseling on shut down.
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