88 XJ wont stay run'n

[Camarokid]

Hello everyone, Ive got an 88 jeep cherokee witht the 4 liter in it, I was in Chadwick messn around and the jeep just died. It would crank but not start. I let it set for a few hours, now it would start and die once i released the key from the start position. If u held the key on start, the engine would run just fine and its not runnnig off the starter. It will idle idle up normally then come down to a regular idle. ( dont worry I only did it once to see if it would run) Is there a ballast resistor in the ignition circuit i dont know about, is it possible the pcm is fried and i was hoping someone had possible had this problem and successfully fixed it. Thanks every one!

[grizzly]

I would check your ignition swithch.  Just something to check out.

[Camarokid]

I replaced it yesterday!  It cost 10$, but still did change!

[xj42]

This thread should help get you going.

http://www.naxja.org/forum/showthread.php?t=101119

[x6xdemonx6x]

could try pulling codes.  turn the key from off to accessories like  3 or 4 times and leave it on the accessories option the check engine like should start to flash.  Example would 5 flashes paus and 5 more then a long pause mean code 55 which means your codes where cleared in the last 30 cycles usually cause the battery was unhooked.

[x6xdemonx6x]

as a add on to that make sure you post the codes up here because in some cases the code could be a few things like on mine it through a map code even though it was the computer i beleave a crank sensor will throw one for a map sensor also

[Camarokid]

Im ganna try the codes in the next day, I found that after the turd starts, when i let off the key from start to just run, I loose injector pulse. I still have spark, fuel pressure and iff i pull the air boot off, spray starter fluid at the throttle body after it starts on the start circuit then when i let off the starter it will run perfrect off the starter fluid and will not require me to hold on ta the key in with the starter engaged. This is so wierd, Ive checked all the resistances on my sensor and important wiring harnesses to sensors and relays!!!

[OzarkMountainCJ5]

Check the vacuum line on your map sensor it will cause some strange things on Renix XJ's. Also check your Throttle position sensor, it should have five volts to it when the key is on. The TPS controls fuel delivery also the coolant temp sensor can cause a loss of injector pulse. Do some searching on NAXJA there is lots of info there. If you have any questions PM me at http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.html there is a good writeup on how to check all of your sensors and what they control.

[x6xdemonx6x]

may be a long shot but check your under hood fuses

[Camarokid]

I fixed this problem over a month ago, but one of the fusable links fried that supplies power to the engine computer, fuel pump and diag port. I couldnt find where is was shorting to ground so I made a new harness with a fuse in it. Vary crappy!!! It would still make enough contact to have voltage present at the computer but would go open when u start it. (couldnt supply the current) Learn form my mess up if ya ever have this issue!!! Good luck!