Help! I don't know what's wrong.

bcox624

New member
I have an 1988 YJ 4.2L I6, manual transmission, with a Motorcraft 2100 carb and nutter bypass.

I recently swapped the carb from the Carter to the MC 2100 and executed the nutter bypass because the Carter took a crap. It was sputtering and wouldn't start at times. I'm not a mechanical genius but the Jeep (I call her Stacy, lol) seemed to be running a lot smoother and it seemed to have more acceleration.

Approx. 2 or 3 weeks after I did the carb swap the Jeep started sputtering HARD. It's undrivable now. It'll sputter and the RPMs will drop from whatever they are at to 0 immediately. And unless I hit the clutch or put it in neutral really quickly then it will stall. Also, when I was on the way home the day that this started happening the Jeep had 2 of the loudest backfires that I've ever heard. They sounded like 12 gauge shots. They were approximately 10 or 20 seconds apart and the second one was slightly less loud. Now the Jeep has a really deep idle and it sound like it has an aftermarket exhaust, which it doesn't.

I took the carb back apart and I couldn't see any clogs in the fuel flow. I could see both of the streams of fuel flowing into both of the barrels when I pushed the accelerator. Now at an idle and I can rev the engine and hold it at 1,500 or 2,000 RPMs without any major sputters. But once I put it in gear and try to go it sputters.

The only thing I can think to do is the TFI ignition upgrade with the bigger distributor cap because it could probably use a tune-up anyways.

Does anyone have any ideas, comments, or clues as to what could be causing this?
 

You have a vacuum leak and blew your muffler apart
 
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