I have a 2000 xj 4.0 (coil pack motor) auto 4x4 that will not start. First let me start by saying it blew a couple fuses several months back. I think the fuses were to o2 sensors and the ignition fuse (blew the mini fuses). Replaced fuses and it ran fine for weeks. Went riding and when it flexed the jeep died like the switch had been cut off and hasn't ran since. It has been at a shot for 3 months now with no luck on finding the issue. We have checked all sensors (all checked good), fuel pressure (46psi +), swapped PCM, checked all fuses and relays etc.


Now to the current problem. The jeep will turn over but not start. The coils are firing but the injectors are getting no power (verified with test lamp). Mechanic is saying the ASD relay is keeping the injectors from getting power. How can I safely apply a temporary power source to my injectors to see if the jeep will crank and narrow some things down. The wiring and connections all check good (I am going to go back over them). Also I never had this problem until I installed an Optima yellow top battery, just a coincidence or could the battery be part of the problem.
ANY HELP WOULD BE GREATLY APPRECIATED!!!! This thing is about to drive me crazy!!

 

Why don't you just replace the relay to at least that rule out. Easy enough.

 

There is a wiring issue that needs some attention.

 

Cherokees have a problem with the O2 sensor wiring in them' tell your mechanic to hook up a labs op to your jeep and read the wave pattern on the O2 sensor. It shouldn't get above .85 volts

 

I know the wiring on the O2 sensors is messed up. I was under the impression didn't have to have the sensors to run, it just wouldn't run the best it could. If they are disconnected or have broken wires, it should still crank and run right???? A friend of mine has his unplugged and his jeep runs fine. Now that I think of it, mine ran fine with sensors unplugged and had been that way for a while

 

We did swap the relay with not one but two new ones. Just to be sure

 

Check your main engine fuse, and make sure it's not blown. Should be a 30 amp mega fuse. If you're getting spark but no fuel, your ASD system is on because either A) Bad ground B) PCM not communicating C) There's a short D) Blown fuse. Those are all from my experience.

 

Smh leavn the 02 sensor unplugged poor jeep

 

Sorry for the delayed update. All the wires in the fuel injector harness were pretty much fused together. So after fixing the injector harness and a new computer, she is running fine. Thanks for all the info, and I hope this post can help someone else!!