This is my first post here but I have done several searches on here from time to time in the past. I am having a starting issue with my Cherokee. I have read countless posts on this issue and and mine is similar but also different. My Jeep has always started very easily until recently. It seems the longer it sits the worse it is. It may start perfectly for days, then all the sudden it will do nothing but turn over. If I leave it and come back in an hour or a day it may start right up. If I start turning it over and stop about three times, sometimes it will decide to start. I have sprayed starting fluid in the breather when it won't start and it seems it's not firing at that moment. It has been in and out of the shop several times this year and it is still not fixed. Mechanic has done fuel pressure test and says it's fine. He has replaced the Crank position sensor, cam position sensor and a relay and I am still having the same starting problem. Yesterday it finally started on the fourth try and the check engine light was on. Tried it this afternoon and it started immediately and CEL was off. It may start for days then all of the sudden not start. My mechanic and I am very frustrated. I have put quite a bit of money in it and I am scared to drive it anywhere for fear of being stranded. I love my Cherokee. I have owned it for 12 years and do not want to give up on it. I can not trust it for myself or even consider selling it until it's fixed. I would greatly appreciate any input from anyone that can give me advice on how I might solve my starting problem. The only codes he has mentioned was about oxygen sensors and that does show up every time. The Jeep runs good when it starts, no skipping or shutting off, only a starting issue. Thanks in advance. Larry

 

Welcome to the forum, Larry.

Questions:

1. Have you verified spark when it does not want to start?
2. What brand of sensors did your parts-swapper use? (He's not a mechanic.) Our beasties are very particular about the crank and cam sensors, in particular. NGK or Mopar ONLY on those and the O2 sensor. Even quality brands like Bosch don't work reliably.
3. What relay did he replace unnecessarily?

 

The mechanic was reluctant to put on the sensors. He said he did not want to just throw parts at it but he did not know what else to do.I have know idea the brand of sensors, but i can easily find out because he charged them to me at a local store. We are a small town and everyone knows everyone. Spark or lack of has only been checked by me with starting fluid, but I will ask mechanic to make sure he has verified it when it fails to crank if there is spark. It's been difficult to diagnose because it does not fail to start but on occasion. I will also find out what relay he replaced. Thanks for your reply. I will find out answers to your questions and get back to you.

 

I suggest you get a spark tester and keep it in the vehicle. They are brain-dead easy to use, and if you have it in the vehicle at all times, you can quickly check it when you have a problem starting.

If he got the sensors at the local parts store, they are suspect. They need to be Mopar or NGK. They are sometimes labeled as NTK. Same company.

Another thing you might want to do is to get . I think it's worth the money to get the http://www.obdlink.com/, because the software is superior, but you can read codes with the basic 20 dollar units. A lot of folks are happy with the BASF unit and Torque, which is freeware. I could never get it to save logs for me.

If you are logging when you are driving around, you might find a smoking gun.

This could be as simple as a loose connection. Once you have verified no-spark (if that's true), your prime suspect is the ASD relay circuit. It supplies 12 to the coils and to the fuel pump.

 

Going to see mechanic and check on make of sensors tomorrow. Thank you BlueRidgeMark

 

My 2001 xj had a problem just about the same . I changed the Auto Shut Down Relay and its been starting just fine .

 

Talked with mechanic today. The relay that was replaces was the auto shut down relay. He said he was not sure if it is not firing and had not done a spark test when it fails to start. Both sensors that were replaced were replaced with sensors by Standard brand from local parts store.

 

It is almost guaranteed that either spark or fuel injection is absent when the vehicle is not starting. Your mechanic should first be prioritizing determining which one of those items is falling out. If both are present, then attention would be turned to the Throttle Body and IAC (Idle Air Controller).


The ASD relay relies on a main 12v feed from the PDC (power distribution center), a 12v positive coming from the ignition switch, and a ground coming from the PCM (computer). If spark is determined to be missing during problem, I would turn attention to confirming that the ASD relay is functioning normally. The relay might be just fine, but that doesn't mean it is being commanded properly. (a worn out ignition switch, a pcm problem (rare), or a wiring problem among any of those could cause the same symptoms).

 

I made a copy of all suggestions and took them to my mechanic. I will post on results later. Thanks, Larry