'GEN' light and bucking

Yesterday my 96 XJ, close to bone stock, began acting up on me. Weather conditions were about 45 degrees and raining and driving along at about 50 mph it began bucking on me, when I let off the gas it would stop. At lower speeds of about 35 and under the bucking was not as severe but the revs were all over the place. I let the Jeep sit for a few hours and the bucking went away but the GEN light came on. I changed the alternator about two years ago. The bucking I was assuming was from putting crappy Marathon gasoline in it and it was just that passing through the fuel system, but the GEN light now makes me think it may be something else. Any help would be appreciated, thank you.

put a volt meter on it running, and off. should be 14~ish volts runnign, if it isnt, your alternator is not charging. OEM alternator location leaves it at the bottom of the motor, ive killed many playing in puddles... dunno how deep of water you were in, but its worth it to check. With your jeep not running, you should have NO LESS, than 12.5volts.

Load Test the battery and the alternator.

Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds.

Yup, a failing alternator will definitely cause all your symptoms

When the voltage drops below around 10VDC, the injectors stop firing. To have instantaneous loss of power and then resumption of power does not to me, sound like an alternator.

If the Gen light (I assume you have only idiot lights, no gauges...) comes on, and stays on, then I would expect to see the engine run OK while the battery is draining down. Once the injector threshold is reached, I would expect the engine to run badly and then stop running altogether. If the light/problem are lock stepped together, something else is happening.

Doing all of the basic electrical maintenance will definately help by eliminating some of the variables. Keep us in the loop on what you find. You may want to consider adding some gauges to your dash to aid the diagnostice. Plus gauges are just plain a good idea. Gauges can be had for cheap.

So to recap, we sort of need to know the timing of the two events. When does the Gen light come on and when does the engine massively misfire.

I had the same thing happen to my '96 earlier this year. Yeah, GEN...cars were using ALTERNATORS over 30 years before the '96's were made! Anyway, the volt gauge was up and down, radio was buzzing, engine running like crap. Went to the store, picked up an alternator, go to remove cables from battery, and I find a cracked terminal! All carboned-up from arcing. I installed the alt. anyway, but probably didn't need it.

Check all your grounds, terminals, connectors, etc. before you climb underneath, but my feelings are that replacing something like this probably wouldn't hurt anyway, but I hope it solves your problem.

I know, a Gen light. Technically, an Alternator is a Generator. It just produces alternating curent that is rectified into direct current. But, yah, it is a generator...