My Jeep started acting as though it was running out of gas about three months ago while I was driving on the interstate at 70mph. It only did it at high speeds at first then it progressed over the months to doing it at start up, idling, and while driving at all speeds. Started dying on me regularly while idling and driving and just today my speedometer started jumping up and down erratically and the rpm's sit at 0 while driving and idling.
I checked the codes and it said 02 sensors.. I unplugged them and the problem remained. While checking the 02 sensors I noticed that the catalytic converter had been removed by the previous owner. I've ordered a new catalytic converter and am parking it 'till it arrives. I've replaced spark plugs, plug wires, fuel filter and the rotary button. Checked the distributor cap and it looked like it was replaced not too long ago... checked the wire from the distributor to the coil and it looked to be in good condition. Checked all fuses and no problems there. I'm at a loss... A buddy tells me it could be water in the gas but I find that hard to believe considering I've filled it up and put valve cleaner in it and the problem still remains. Any help will be greatly appreciated as I'm merely a mediocre mechanic and out of ideas... pcm? map? cps? I don't want to spend a lot of money, considering I don't have a lot of money, guessing on which/what it may be. Thanks.

 

If I had to guess I would have to say it sounds like a bad ground. Check all of your grounds. check the one on the firewall to the head, and the ground bundle at the dipstick tube mounting bolt. make sure they are in good condition, clean and tight.

 

Cleaned and tightened all the grounds but the problem remains. I read somewhere on here that the PCM may be the culprit so I went on eBay to purchase one but for the models they have showing for the PCM's that ate supposedly for my year doesn't match the numbers exactly... Does that matter? Since mine is a 4x4, 4.0 does the PCM have to be out of the same characteristics that my jeep has? Thanks for the help... It's greatly appreciated.

 

No issue with o2s wiring contact each other or ground to metal.

 

I think you can swap them. I have not done it personally but I am sure someone on here could tell you

 

Did your temp gauge appear to read cooler than expected? If so, you may want to replace the coolant temperature sensor ($20+/-). If the sensor is bad, the computer makes the engine run too rich and causes stalling. Just fixed that on my '98 Classic and seems to have worked.

 

No the temp gauge seems to have been working normally... I'm not able to drive it at the moment as I can't accelerate without it backfiring and missing so I can't check to see if it is.

 

Wiring from plug to harness checked out good I guess, its telling you o2 circuit issue ?

 

96 still has separate temp sensors for the gauge and PCM.

Have you checked the output voltage from the TPS? Center wire- key on, engine off.
Less than 1V with the throttle closed, rising to about 4V with the throttle wide open.
Watch for a smooth voltage increase with no flat spots or dropouts. If it thinks your foot is off the accelerator you won't get enough fuel.
How about the fuel pressure?

I believe '96 was the first year the tach signal arrived over a CCD bus. I'm less familiar with that than I should be, but can't help wondering if a fault there (or perhaps simply in the PCM or connectors) is also behind your stalling and backfiring problems?

 

Check to make sure there are no loose connectors anywhere. Had a similar problem with our 94. I had unplugged a wire to get at a spark plug and forgot to plug it back in. Check engine light came on, speedo quit working, and it would die every time I stopped.

 

Yes the wiring is intact and not grounding against anything. The codes said the o2 sensor was reading lean.

 

I'm out of town at the moment but I'll check the TPS when I return in two days. How would I go about checking the fuel pressure? Never had to before so I'm unfamiliar with it. The center connector of the PCM wiggles just a lil' bit and I read on another post that sometimes it loses connection causing these problems so when I return I'll check those as well.

 

I checked the wires multiple times just to be sure and they're all working properly. No shocks or anything with the motor running. Checked it at night also to make sure it didn't look like a lightning storm under the hood.

 

Im having the same problem with my 96 Cheorkee Country, Ill be driving around and all of a sudden she'll stall, or give some form of hesitation/loss of power. I brought it to a friend of mine who owns a shop, and he thinks it might be the PCM.
Any reliable places to purchase a new or reman PCM??

 

Update: Have changed the tps, cps,iac, map, coil ,coolant temperature sensor on the thermostat housing, plugs n wires, cleaned throttle body, checked and cleaned all grounds and connections, fuel pump is fine... I have the temp sending unit part number 56027012 that connects on the back of the head by the valve cover but the male connecter to the pigtail is broken and I can't find the pigtail and connector anywhere online... anyone know of any place that sells them? Thanks