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Tech Xpert
Tech Xpert, ASE Certified Technician
Category: Jeep
Satisfied Customers: 292
Experience:  33 Years experience ASE Master Tech, 27 Certifications, L1 Advanced Diagnosis
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1989 Jeep Wrangler Sahara: 4.2L/inline 6/ carburetor/150,000 miles

Resolved Question:

I have a 1989 Jeep Wrangler Sahara, 4.2L/inline 6/ carburetor/150,000 miles. The problem I have started all at once. I went to start it and it's like it started, but didn't fully start. The engine shook and "stuttered". It was as if it were only firing 5 cylinders. Then it "cleared up" and ran normally. The next day it did the same thing, only worse. I could drive it but it would only go at maybe 15 or 20 mph tops. After about 1/2 mile it "cleared up" again and ran normally. I took it to a couple different mechanics They installed new plugs, adjusted the carburetor, replaced the PCV valve, oxygen sensor, and checked the fuel filter and pump. Same problem happened. The last shop gave up, after a few weeks of trying, said they thought it was the computerized carburetor that was the problem but there weren't any diagnostic tools for diagnosing as Chrysler only made these carburetors for a few years then went all fuel injection. Can this jeep be saved or should I donate it?
Submitted: 8 years ago.
Category: Jeep
Expert:  Tech Xpert replied 8 years ago.



Thanks for your question. I will do the best that I can to help you.


It could be the spark plug wires or the distributor cap or the rotor. It also could be the ignition coil. There is a chance it could be the carburetor too and there is an outside chance that it could be the ignition module or the distributor itself.


I would recomend to start changing the cap, rotor and wires. We need to eliminate this and it won't cost too much as it is necessary maintenance anyway. After this, see how it runs.


If it still does it, then I would recomend taking a small propane tank and hook a hose to it and stick it into the carb while the engine is running. This will enrichen the mixture and if it is running lean, it will start running better with the propane.


Let me know how you make out and I will keep helping you until we get this solved.




Customer: replied 8 years ago.
I had a tune up done 11/12/2007 which replaced the dist. cap and rotor. I wouldn't think they'd need replacing as I don't drive it far to work and back. I've had this jeep since 1992 and I never had this particular kind of problem before. Usually I can guess what the problem is since I had it before. My guess was some sort of fuel restriction (filter, pump) but they were checked as ok by the mechanics.
Expert:  Tech Xpert replied 8 years ago.

If it was the carburetor, it would have to be either too rich or too lean. If it was too rich, you would see gas dripping down inside the carburetor while it was running and doing the problem. Take the air filter off and get yourself in a position to look straight down the carburetor and see if you notice any gas dripping down. At idle, there should be no gas dripping down at all.


If it is too lean, then if you add propane to the carb, it will run better. If you suspect the carb to be the problem, do these tests so we can get some kind of direction.




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