Jeep Cherokee Sport 4.0

[Jim Uran]

Great motors! 1999 with 164,000.I bought this as a side vehicle about a month ago. But I've been scratching my head for a week now, initially the Jeep ran fine then it started dying after about a 30 mile drive. ( I happen to work about 30 miles from home ) Once it would die it wouldn't get any spark until it cooled down. After anywhere from 5-30 minutes it would cool down and catch spark and fire right up and be fine for another 30 mile trip lol.

That lasted about a week, and then one morning I started it up to warm up, went inside and when I came back out it wasn't running, it would fire back up and die out like it wasn't getting any gas. I checked the pressure at the fuel rail and it was about 45 PSI which seems fine to me. Now she won't even start at all.

On a side note, I did replace coil, plugs, wires, Distributor cap, and rotor.

Anyone have any ideas? I know the Crankshaft position sensor has been known to raise heck, and also some sort of problems with an Anti theft system that will shut off fuel flow, but it's still getting to the fuel rail with a lot of pressure..... I don't know I'm baffled.

[Jeremy airjer W]

Do you have spark know that it won't start?

Sounds like a crank sensor might be the issue.

There is also an issue where the IAC will stick in the bore. To see if this is the problem give it a little throttle when it starts and see if it stays running. If it does until you let of the pedal than pull the air tube from the throttle body, you will see the air bypass passage to the side of the butterfly. Look in that passage and you will see the IAC pintle. Use a small screw driver to gently work the pintle back towards the IAC valve body. Then start the vehicle and see if it idles. If it does replace the IAC and thoroughly clean the passage. The pintles will wear and just cleaning may solve the issue temporarily but it will happen again if the valve is not replaced.

[Jim Uran]

No spark at all now....

it's definitely something electrical IMO... I really haven't had the oppurtunity to fart around with it as much as I would like to. I'll give it a good looking over again this weekend and swap out the crank sensor with another one from my bro's jeep. Same make and year.

[Jeremy airjer W]

Unplug the coil. Have a voltmeter Or test light on the power wire at the coil. Turn the key on, you do not have to crank. There should be power at the coil for a couple of seconds as the sad relay is energized and then deenergized. If there is no power unplug the crank sensor. The connector will be near the firewall by the intake. Recheck for power. If you now have power the crank sensor is shorted and needs to be replaced.

[Jim Uran]

Thanks Jeremy.. Will do!