My '96 XJ has been my daily driver for years/decades now and she's got 220k miles behind her. My Mom's car needed some work so I traded cars with her while I get hers done. She doesn't drive nearly as much so it's only been started once every week for about the last month. On Tuesday of this past week Mom leaves the key in the ignition and turned forward to the on position so she can close the windows. Well, she forgets to take the key out so it stayed in that forward position until yesterday when she went to start and it was totally dead. Yesterday she and a neighbor jumped it 3-4 times, the engine starting each time with a little gas pedal then it stops.

So I get on scene today and charge the battery up real good, and crank to start without giving any gas pedal and it doesn't start. So I charge again and try to start WITH a little gas pedal and it starts right up, but you have to keep the RPMs up to keep the engine going. After starting I let the engine run at about 1500 rpm for about a minute, and as soon as I let off the gas the engine goes back down to idle and dies immediately.

So at least we know the engine runs, which cuts out a lot of guess work. Now I need to figure out why it won't stay running.

Any ideas? What should I check?

Thanks.

PS. All fuses are good and the fuel filter is only a year old.

 

If the battery is really drained, it will not run. Put a voltmeter on it or see if it will crank with headlights on without having it jumped..if it does then sadly not your issue. If battery cranks normal with lights on, then she might have jammed the IAC valve and its stuck in wrong pos.

 

I agree with the above answer, with the proviso if its got enough charge to crank and start fine, that would normally mean its got enough voltage to run the electronics

The scenario where a vehicle is jump started is different, as the battery is dead flat, and the alternator takes a fair while to charge, and can lead to low voltage

some things to check

The battery voltage after sitting overnight should really be over 12.25V..that is roughly a 50% battery, if it is lower, I would bite the bullet and get one, or take a big risk later

In the meanwhile, if it will start, hold the RPM above 1500 for 5-10min, it should idle then, if it stalls, try just ordinary no throttle starts a few times, if this does not work, you need a new battery, or something else is wrong

Put an OBD2 reader on it

check for any looseness in air filter gear, vacuum hoses, fuel leaks

clean IAC with throttle body cleaner

 

My 96 does this once maybe every couple months. It’s always in the morning when I have to get to work, so I don’t have time to mess with it and I just run with it. Hold the throttle down enough to keep it running, till it warms up then all is fine. No codes. To me it feels like a stuck open EGR, since when the IAC sticks on my other cars it’s more of a stumble and surge situation. The Jeep just stops quick.