I've track down a few shorts in the wiring, a mouse got to work in the dash. I've replaced the ground cable which was shot. Now the Jeep starts right up, seems to be holding a charge but after idling for two or three minutes it shuts down abruptly. are there sensors somewhere that may be doing this. When this Jeep runs it is still very strong. I've owned it for 20 years and I think it has another 50-100 k left in her. Any help would be great. It is the 4 liter six, fuel injected. Thanks, John

 

after it stalls does it start back up could be CPS theyre known to do this

 

X2 on the Crank Position Sensor...Tj

 

Yes it will start after it sits for awhile. Runs for 45 seconds or so then stalls. It will run longer if I hold the gas pedal down. Was that a sensor you mention?

 

CPS may just need the plug in connector cleaned. I have seen several that are bad but none that would allow it to run for 45 minutes before dying. Clean the connector and see if that helps.

 

Ok, I agree it may be the CPS but, WOW how do you get to it? I don't have a lift or a trans jack. Any advise?

 

After a three day affair I replaced the CPS. Easily the hardest thing I've ever done on this 89 Jeep. It turned over for a moment but then died. Before replacing the sensor at least it ran for a few minutes. Any thoughts?

 

im not 100% but if my jeep was still doing after the cps swap i would replace the fuel filter. it is in the gas tank but itll be much easier than the cps. i cant guarantee anything but like you said if you hold the gas down itll run longer, i would say fuel filter. good luck, hope you find it out

 

Earthtojohn I am leaning toward it being a ground. The ground between the head and firewall is frequently the culprit. Take it loose and clean or replace it and clean the attaching points with something like a wire brush. Get to good clean metal.

As for the fuelfilter it is possible but unlikely. You may need a new pump if that is the case. The filter is nothing much more than a sock which covers the fuel pickup and of course the external fuel filter which you have been changing with every other oil change.
You do change that external filter don't you???

 

Ray and Blue, This is the first time I've ever found an internet forum TRULY useful. Thank you all. The fuel filter and pump was another saga a few months back. A local garage replaced the pump without pulling the tank, I'm sure Blue knows that this is the fastest way to lose the sock filter. So with a wicked case of vertigo, a lasting reward from a motorcycle wreck, I pulled the tank. Cleaned it ,painted it and remounted it with turnbuckles from my hardware store. The filter was replaced 1600 miles ago. Blue mentioned the rear ground strap, it does look funky. Seems the same local shop replaced the bolts to the valve cover and never tighten them down. I'm sure this is what fouled up the CPS, there was oil everywhere. In the morning I'll address that rear strap. I'll be home in Au Sable Forks NY until I figure this out. Drop by any time for coffee- 9 north main st. across from Stewards market on 9n. This is great country for a drive and I can park 8 to 10 Jeeps in my driveway. Give it some good thought. peace, j

 

Hello, I've replaced the rear ground strap as advised by Bluexj. It started right up. As I was gloating about my blind determination it died again. Seems I'm back to 90 seconds of idle then death. I'm going to go ahead and replace the coil, wires, plugs and dis cap-rotor tomorrow. I'm praying that works, I've maxed out my credit on a small vending business counting on this jeep to run. Thanks to all of you out there who have chimed in.-j

 

I know this may sound like it won't fix it. But I had that exact same prob and mine is an 89 also with the 4.0L... I checked everything on my jeep and it kept dying. I worked my way from the motor back and nothing worked till I changed one thing and now it runs GREAT!!! The fuel filter... I changed my fuel filter and when I went to turn my jeep on I had my friend push the pressure release on fuel rail and he held the release to get the air out of the line for prolly over a min and after that I have not had any problems at all keeping my jeep running. A filter is only ten bucks too.
It took me about 4 or 5 days to finally get it right but after I changed my filter it still wouldn't start but if you push the pressure release and hold it and it doesn't push gas hardly at all then it's the fuel pump but if you take off the filter and the side that the fuel goes in from the fuel tank if you turn it up and dirt and grim comes out change it. But I beat it's the filter. The fuel filters last quite a while and my fuel pump is about 12 years old and still going great. my filter on the other hand was shot.

Try to see if you are getting any pressure on the fuel rail and if not take the filter off and see if their is grim in it if not fuel pump is prolly out. Hope this helps

 

could also be an IAC ive got the same problem but i get more run time then you do and i just changed my CPS yesterday and its a bit of a ***** but i made it worth it as i had to put in the 2 upper bellhousing bolts that some hack mechanic failed to put in when they swapped the engine and changed my trans mount as it was like a marshmellow and my trans shook way to much

im doin the my IAC tomorrow so ill update when its in if it fixes

good luck

 

I do not know what the IAC is so I’ll do a little research on that. The fuel filter has less than a thousand miles on it. I changed it after the tank was pulled and cleaned. New fuel pump too.
When I first started looking for shorts in the wiring I thought the problem might be the ignition switch. I unbolted it from the column only to find another switch which looked more like the photo in my Haynes manual. When I unbolted the thing a rod coming from the ignition key lock came out. It will not seat back in. This first switch does not appear in my manual or in any online parts catalogs. So my question is what is it? The jeep turns over without the rod which I thought at first was a momentary contact switch. Just wondering if this is somehow connected to my stalling issue. Thanks-j

 

got no clue bout the ignition switch issue but the IAC is is on the passenger side front of the throttle body