I was driving home tonight when the Jeep stalled at a stop light. I tried to restart the car twice, which it did start and run the both times tried to start it for about 3 seconds each time. Then after the second time, the car would not even try to fire up. My initial thought was that it died do to lack of fuel, but when I turn the key into the on position the pump comes on for about 2 seconds. So my question is, what might be some of the things I should be looking in relation to the fuel system, and how do I test for those items. Also I understand that the CPS can be an issue and I am going to check it first thing. But other than the CPS, are there any other sensors that are notorious for causing this sort of issue that I should be looking into? Or any other types of issues that I should be looking into for that matter. Thanks

 

Definitely look into the crank sensor first. It is the most common engine management sensor failure on the 4.0 and your symptoms match up with it being the primary suspect.

If you buy one, buy it from Jeep. Well worth the little extra money in reliability. No lack of threads of people having trouble with some (not all) aftermarket crank sensors.

 

Ok I will definatly check that first. A small clarification though, would a CPS failure trigger a CEL? The reason I ask is there was no CEL activated, and I am just curious. Thanks

 

It failing would, however melted wires from the CKS wouldnt, so check the wires going to the CKS first.

 

Ya, I plan on giving everything a good once over when I am under the hood and I will check the entire circut to ensure it's integtrity.
So, I went out to the car and for SnG's tried to start the car, which it did fire up and run. Again, there was no check engine light. I shut the car down and again for SnG's I plugged the scanner into the car. There were NO stored DTC's that popped up immediatly on the scanner. But when I went further into the scanner menu under, if I remember correctly, "stored engine codes" I found a P0320 Ignition/Distributor Engine Speed Input Circut Malfunction. So in other works a crank position sensor. So my question is, why didn't it throw a CEL? And under what condidtions does the computer decide to trip the CEL or store the code? At this point I am questioning my fundamental understanding of an OBDII system.

 

If none of the other stuff pans out that you are checking, do a fuel pressure check with a hand held guage at the test port on the fuel rail. I wouldn't rule the fuel pump out just yet. You can hear the priming noise when you turn the key on and still have a bad one.

 

A failing crank sensor only trips a check engine light about 25% of the time. I've been to this rodeo many times.

 

Well I went ahead and got the sensor changed out and I will say this, that I hope the son of a $itch who thought to put that sensor there, is somewhere in hell praying for ice water right about now. Other than that, the car started and ran in the driveway but I have yet to take it out and see how it does. I will report back tomorow and let everyone know how it went. I guess if the problem persists then I will have to check the fuel presure. Thanks to everyone who provided me with input, it is greatly appreciated.

 

So just to cap off the thread, it was the crank position sensor. Replaced and the car runs fine now. Also to elobarate on not getting a check engine light when the sensor failed: When I hooked up the scanner and after the scanner told me there were no DTC's I went into the "enhanced DTC" menu of the scanner and that is where I found the code P0320. Again, thanks for the input folks.