Question about 1996 Jeep Grand Cherokee
1985 cj runs starts good but won't keep an idle
Assuming that the jeep has not been modified it is likely the Carter BBD Carburetor on that engine, or the sensor inputs to the carburetor.
The Carter BBD has an idling circuit that is always seeking. There is a stepper motor that keeps changing the rpm, and fuel mixture. It basically never stabilizes, and it keeps adjusting based on the feedback loop from half a dozen or so sensors.
So, if a sensor goes bad and feeds a constant signal to the carb, you get problems.
The Carter BBD is a very difficult carb to rebuild and is usually fairly dear in terms of cost.
If you can find a Jeep factory repair manual (on ebay) on the 85 cj -- it is an olive green manual about 3 inches thick and is usually not too expensive, it has troubleshooting procedures for the BBD. Don't get a Haines or aftermarket manual. get the olive drab official factory manual
Remember it is probably the carb that is bad, but there may be more to it than just that.. I don't remember all the inputs to the stepper motor circuit, but I do know that EGR valve is one of them.
Posted on May 16, 2009
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Posted on Jan 02, 2017
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