Alright, It's been a while since I've been on the forum lol.

But to the point. 1992 XJ 4.0 with the 5-speed. 228kmiles

Most of the time, after it sits for at least 5 minutes, it has a starting issue. Occasionally it starts just fine.
-Cranks just fine, but will only fire if I hold the throttle wide open. (Right here I'm presuming doing so is causing the PCM to go into a flood clear mode). and even then it takes about 15 seconds before firing.
-Priming the fuel pump makes no difference, I'll cycle the key 3 times until the pump stops kicking in, doesn't help.
-When it does fire, black smoke comes from the exhaust
-Once running the engine misfires for about 5-15 seconds, slowly smoothing out. If I try driving it stalls
-Driving, the engine keeps wanting to idle around 1,200RPM while the jeep is moving. Eventually it does calm down, but not within the 6 minutes it takes me to get to work.
-Also has an intermittent hesitation when getting the the throttle with a load on the engine

Asked for advise on a local XJ Facebook group, some folks pointed me to the Crank sensor, so I tested it based on an online service manual at my job. Which, was to test resistance between pins A and B, if there was any resistance the senor needs to be replaced. My meter read about 4.3miliohms.

So I'm looking at the sensor, but I want you more experienced guys to give your advise before I throw a $60 part at the Jeep.

 

CPS is possible.
But I would do a fuel pressure check after engine shut off. See if you lose pressure fast.You could have a fuel injector (or several) leaking, causing exactly the same symptoms as you describe. Would also explain the starting in clear flood mode and the rough idling after start up....

 

if you are using a good quality meter, then I'd plan on replacing the sensor.

 

I'm looking at this now, just gotta get my hands on a gauge. Threw the new CKP in since it was going bad, and I'm sure it was the original so w/e. Made no difference.

Was gonna try listening to the injectors and make sure they all click until I could get a gauge.

 

Okay. Got my hands on a fuel pressure gauge and hooked it up. And the problem refused to replicate itself.

But, I did notice the fuel pressure was consistently 4psi above spec both at idle and with the pressure regulator vac hose unhooked (was using my coworkers fairly-new MAC set). Shut the engine off and let it sit for about ten minutes, checked the pressure and it actually went from 35 to about 43psi.

But like I said, the issue went away completely now. Took the Jeep to work, did the test, drove it back, went to the parts start later, nothing. Guess He was just mad at me...

 

Once you got the gauge, now its scared

 

I'm wondering if pulling the fuel rail out the night before did something. Because it's still running just fine. I dunno, nor do I care since he's running again lol. Now to figure out where this damn belt squeak is coming from...

 

maybe disconnecting the rail dislodged some debris