Hi, I have an 89 YJ that after I shut off the ignition it will keep turning for a few seconds and then shut off. Not sure if it needs a tune-up or fuel or something else. Also lately has been running sluggsh and hearing some exhaust noise from the engine bay. It sounds like it's coming from the manifold. May be related but not sure! I drive this thing 40-60 miles daily and has not given me any problems til now.
It's called dieseling and can be caused by a bunch of things. Usually it is due to bad seals in the carb. Might check the manifold for cracks but dollars to donuts you need to rebuild the carb.
Sluggish could be a clogged cat or vacuum leak at the base of the carb. When you rebuild it don't reuse the old gasket, put in a new one. The easy way to check for a vac leak is start the engine and spray carb-cleaner around the base of the carb. If the engine hessitates you found a leak.
It's been a long time since I worked on carbs, there are several others in this newsgroup that have probably done one this year and have more current braincells than myself. :)
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