I have a 2000 Jeep Cherokee Classic 4.0 engine. Recently I've been having a few problems with it, about 2 weeks ago I replaced the plugs and rear o2 because it had a misfire and was throwing a code for the rear o2, and I also replaced the thermostat just for the hell of it with a high-flow one. After install the misfire was gone and the engine light was off

2-3 days prior to this I went to start my jeep after driving and letting it sit for a while, and it turned over but cranked really slow and sluggish and did not start the first time. The cranking slow and sluggish problem happened a few times before and after but always started.

So I took it to the garage to have them run it for codes, in result I have a new rear o2 sensor which was needed and the new plugs solved the misfire. I told the mechanic what had happened and he said it could be a failing CPS. This after reading forums until my eyes hurt I found out that if I was going to get a new one, the aftermarket ones are a hit and miss sometimes and a new one from the dealership was the way to go. So I figured I would hold off for a day or two before buying one.

I was out the night after this for a rip and after driving for 2-hrs in town and all around my jeep had a drop in the RPM for a sec then came back up to normal, just like it was some kind of misfire and then about 100 meters past that it just shut down and died but the power stayed on along with all the lights and gauges, if I remember correctly. So I coasted into the dodge dealership ironically because it happened just before I passed by, turned the key off put it in park and it started right up again. So I drove around a bit more and went home.

The next day I went to start the jeep and it started for a sec and then quit, I had to crank it a few times after that and finally it went so I gave it a few shots of gas and it stayed running. I went for a drive and came back, shut it off and it started right back up. The next day I started it up and moved it. It sat for a few days and I went out tonight and tried to start it but when I turned the key all the power and gauges came on but it did not crank, not even a click.

I now have a new CPS from the dealership and I ordered a new camshaft position sensor just because the housing on mine had a crack in it (it’s been there since I had the jeep)

After hours of reading I figured that it could be a:

- Bad CPS sensor (which I have but didn't get a chance to put in yet)

-camshaft position sensor which I should have tomorrow

-Bad or malfunctioning NSS –neutral safety switch (which can be cleaned I read and watched a video on)

-bad or malfunctioning ignition switch and ignition actuator pin (which I don’t think is the problem because when you turn the key it feels like it always has, not ruling it out yet)

-possible bad starter (needs to be tested)

-heat soak where my injectors and fuel rail are becoming too hot and the fuel is evaporating after the engine is shut off and causing vapor lock…( figured this could maybe have something to do with it were my jeep does not have the heat shield between the manifold and fuel rail/ injectors.) I’ve never had any issues with this before so I am sceptical that it is the issue.

-starter relay and or engine and relay/ fuse box grounds

Any suggestions or advice on this issue would be greatly appreciated!
, Thank You!

 

What's the code and fuel pressure in psi?

 

I have no idea what the fuel pressure is, I would have to get it checked at a garage and as far as I know there is no code being thrown right now. except for the one before which was for a rear 02 sensor and I'm not sure what that code was.


I also went out this morning and it started right up but after 30 seconds or so there was a few drops in the RPM's kind of like a misfire but more noticeable and then it shut off. started back up, ran for about 20 sec. and shut off again. the third time it just cranked over and never started, and the cranking got slow and sluggish.

 

I am having a similar issue. I think yours may be that crank sensor. Check and see if you are getting spark at the coil post and on the coil wire. Mine is not. Check your ASD relay. Meter out your ignition sysstem wiring from your PCM to all the sensors. Check fuel pressure at rail as mentioned earlier. Hopefully these will help you. I have done all those except fuel and I have no spark at coil. Just can't figure out why. Good luck. I have a 97 Country.

 

Yesterday i replaced the CPS sensor and the camshaft position sensor as well, and in the process figured out a super easy way to get at the cps sensor that didn't involve 2 feet of extensions and a universal style socket. I also pulled the coil back off and filled the rubber boots with Dielectric grease which is awesome stuff by the way! while i was at it i pulled every plug and fuse i could cleaned them with electrical contact cleaner and applied some Dielectric grease, after that i pulled the power wire and plug-in off the starter and noticed that one of the bolts on the solenoid was lose, so i tightened down the nut cleaned all the contacts, applied Dielectric grease and installed them back.
I did a bit of wire tucking, cleaning up under the hood, then made my own heat shields for the injectors. cleaned the connections and posts on the battery with light sand paper as i did on the starter power wire and the main power and ground for the fuse/relay box and called her a day. with much hope and prayer the jeep fired up first turn of the key so i got cleaned up and took it for a drive and as of today it is still working fine (fingers-crossed). first chance i get i will get the fuel pressure checked as well to be on the safe side. SGD hope you find your problem to!

 

^^^ as for the fuel pressure test its prob much cheaper to buy a FP test gauge at harbor freight for around 30 bucks then take it to a garage to have it tested, Food for thought