rough idle at cold start choke problem?

When the engine is cold, remove the air cleaner and open the throttle about half way. the choke plate should shut on the top of the carb. It wont close all the way, but should have about 1/8" gap left. When the choke closes, it will also actuate a fast idle cam on the carb. This will hold the throttle open a bit more than normal. Once you start the engine the choke should open a bit more. By the sounds of your description, it sounds like your choke plate isn't closing enough or at all. If this is the case it is probably a bad choke spring, or possibly the wire feeding it voltage is broken or unhooked.

Chris

The choke should close all the way when cold, and the engine not running. If it doesn't, something's wrong.

Also, the wire going to the choke operates the heater to open the choke, not close it.

I was shooting from the hip here since I don't have a Jeep, but many carbs have a small gap left where the choke doesn't close completely. Maybe his doesn't.

Yup, my bad. Not sure what I was thinking, it's late. ;-)

Chris

The choke is closed by a spring. Mine had the same problem. Here's the thread:

I have seen 3 or more chokes seize up on the BBD carbs.

If you follow the linkage from the choke plate down the side of the carb to the lever coming out of the electric choke unit, make sure that lever can move.

The lever is on a bar that hooks to the choke spring. This bar can and will seize up solid where it goes through the metal case heading to the choke spring.

I have had to remove them to clean them right. I got mine working for about 6 months by using penetrating oil and working it with pliers, but it still seized. After dismantling it and cleaning it good, it has stayed moving.

The others have posted good ideas too.

Mike

Sim>

My 89YJ exhibited similar symptoms. The choke thermostat spring just weakened over the years. I replaced the whole carb with a remanufactured Autozone unit, complete with choke assy. for about $130. Jim