[Jar06896]

I've gotten my jeep ('88 4.2, 5 speed) to the point of running and driving, more or less. I'm looking for some advice on choke settings. I've followed most of what I can find, but still don't have it quite right. I'm running the Carter BBD, and with two pumps of the gas turn the key and she fires right up. After roughly 20-30 seconds I can blip the throttle, and the idle comes down from about 16-1700 rpm to about 1000. I'm finding though, the choke seems to open up too fast from that point, and it's hard to keep her running without manually closing the choke or keeping my foot on the gas. Would the automatic choke need to be set more rich, to hold the choke plate closed longer? As a point of note, it was 30 degrees when I tried starting this morning. Thanks in advance!

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[Got it at last]

If you are only experiencing the above in extremely cold situations, but not when you do a cold start say later in the day when its say 30* warmer you can adjust the preload on the choke by loosening the three screws on the retainer ring and rotating the choke to tighten close the gap on how far the choke plate closes. tightening the preload will make the choke plate take longer to open, loosening it will lessen the time it takes to open fully.

If it does the above symptoms all the time no matter what temp, you are more likely to have a vacuum or carb adjustment issue.

Note...Tightening the preload will help, but not always completely remedy the problem on extremely cold starts. The best remedy is to let it run a little longer and get the engine temp a little warmer before kicking down the choke with the pedal.

I only deal with 40-45 degree cold starts during the winter, 60-85 degree during the rest of the year. I adjust my choke at the beginning of winter for cold starts, the back again as soon as nighttime temps hit 50*, It took a few adjustments to get it right, but I put a couple marks on the choke body for my settings so it only takes a minute now.

Always make your choke adjustments with a cold engine.

 

[12b]

Never did trust automatic chokes I've always converted them to manual chokes. Then Fuel injection became popular I don't think about chokes anymore.

 

[Jar06896]

GIAL-

Thanks for the reply. When I was working on the jeep in my shop, it was 50° and I had similar issues. Today was the first day it sat out in low temps. I'll consider adjusting the choke first, then look for vacuum issues. Once its warm it idles at about 700 rpm pretty cleanly. There's probably still some old fuel getting pulled through.

I did adjust the idle mixture screws while tuning, but maybe a run through the entire system is in order to make sure all is tight.

Thanks!

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[Got it at last]

One of the common downfalls on these older carbed jeeps is the idle tuning when cold. If your really lucky you can get to almost perfect. The rest of us just deal with it and try to get it as close as possible....Sometimes it's just the slightest tweak. Don't worry about getting it just right, work towards improvements and keep good notes as you go. Ambient temps play a huge part in the process, try and do it at around the same temp and a run in between. Sometimes you need a good run down the road to clean 'er out so you are starting off with the way you brought it back warm and shut it down.

Good luck