Hey guys and gals,

My '98 XJ (pretty much 100% stock) suddenly stopped starting yesterday. Before that, it never had any trouble and ran fine.

It cranks as long as I hold the key in "start," but that's it.

One thing I noticed is that the fuel gauge doesn't move when I turn the key to the "ON" position. Previously, the fuel gauge would show the correct fuel level when the key was "ON."

I just filled the beast up two days ago, and there are no fuel leaks anywhere.

Bad fuel pump?

Thanks for your help.

 

To test your pump have someone turn the key to the on position while you lay by the gas tank. If you hear a buzzing sound that is your fuel pump kicking on and priming the system... If so move to your fuel rail under the hood and check for pressure. In none, check for spark. In my 95 that just did this to me. It was my crankshaft position sensor. I got to it after I changed cap, rotor, plugs, wires, ignition coil, and checked over my whole fuel system. But yea good luck man hope this helps bro.

 

crankshaft position sensor...just changed mine to did the same thing.

 

if it starts when you are pressing the gas pedal its probably the IAC valve in the throttle body, if you check the fuel rail for pressure with the key in the ON position could be your fuel pump

 

If it turns over, but doesn't start, you really should verify if you have spark or not.

Remove a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.

Once you know IF you have spark and IF you do, if the spark is good quality, that really eliminates a lot of the suspects.

If you have good spark, try spraying a small amount of starting fluid or a splash of gas into the intake. If the engine starts and runs momentarily, you have identified a "fuel delivery problem"..

BTW, the #1 cause of no-spark on the Jeep 4.0 engine is the crankshaft position sensor. The #2 is probably the ignition coil.

Good luck and let us know what you find!

 

Just to follow up, you guys nailed it.

It was the crankshaft position sensor.

To add a few tips for those who might be troubleshooting this in the future:

On my 1998, normally when you turn the key to the "ON" position, the gauges come up normally. In other words, you should see the correct voltage on the battery gauge and fuel level on the fuel gauge. After the CPS failed, neither the fuel nor battery gauge would move, and the check engine light would never light.

As soon as you disconnect the faulty CPS and turn the key on with no CPS connected whatsoever, your battery and fuel gauges will work again. I don't know if this is a sure-fire way of troubleshooting it, but it was the case in my situation.

Now let me get one little rant off my chest:

DON'T BUY THE CRAP-*** DURALAST BRAND CRANKSHAFT POSITION SENSOR FROM F$*&ING AUTOZONE. THE DAMN CABLE IS TOO SHORT, RESULTING IN AN EXTREMELY TIGHT CONNECTION. IT WILL COME UNCONNECTED, AS MINE DID AS I WAS HALF WAY OUT OF THE ROAD IN MY DRIVEWAY COMING BACK FROM MY TEST DRIVE.

Sorry, but I am pissed. Those of you that have changed these sensors know what a pain it is to get the things unbolted and re-bolted. Now I have to go through the whole ordeal again because some clown decided to manufacture the Duralast CPS with a cable that's about 2" too short. AKJSLFDKJLAHGLKJH!

Oh well, thanks guys for the help. You saved me a lot of money despite AutoZone's crap.

 

Another update --

I went to a local independent auto parts store and bought a second sensor made by Standard. Of course, I left for work forgetting the factory one for comparison. I bought it anyway, thinking I wouldn't have bad luck twice. Well, of course I did. The Standard brand sensor was to f'ing short, too!

Finally went to NAPA and they had exactly what we need. My recommendation: by from dealer or NAPA. Its worth the few extra bucks.

 

Dude I got mine from AZ and it was plenty long... just sayin.. Sucks it happened twice to ya.

 

AZ is my last choice for parts. After replacing the PS pump THREE times in two years I have had enough of their crap parts.

From now on its NAPA for this XJ.

 

If you don't mind the wait you can order OEM dealer parts from Moparpartsonline.com for insanly low prices. I picked up a TPS from there for a good price and the CPS is like 95.00. The shipping was pretty fast also. My jeep breaks down so much it cannot be a daily driver so I can wait on shipped parts.

 

autozone did that to me when i was replacing my trackbar. those dicks have no idea what they are talking about haha advanced has all the hard to find parts i need that napa normally doesnt. I do prefer napa though... even though it always smells like a retirement home in that ish haha

 

Moparpartsonline.com excellent source for original equipment parts.

The crank sensor is one item that I always buy OEM. I personally have had poor luck with aftermarket crank sensors and by the multiple threads every week, so have others. Considering it is the most critical engine management sensor on your XJ, it is WELL WORTH the extra money.