96 grand cherokee 4.0 was would lose power then pick back up was idleing really ruff shut off went back after acouple of hours tried to start then just died won,t start no spark replaced coil wire cap and...
A very similar experience happened yesterday with my son's '95 Cherokee Country, same 4.0L engine. Suddenly jerking, trying to die, then catching again. When he stopped and turned the car off, just like yours, wouldn't start and no spark...and in his case, bad fuel pump, too.
After changing that, we started looking for the no spark problem. First checked the dark green wire (+, or the power feed) to the coil, and nothing there with key on. No voltage. Strange, so I went back and rechecked all the fuses in the little box by the battery. All good (a very easy way to check a fuse is with a testlight: Just clip the lead on the negative battery post and, with key on, use the probe to touch the little slot on each end of the fuse. When ignition key is on, all fuses are powered, and if the testlight lights up on both ends of the fuse, you know it's a good fuse. You don't have to pull it out to check it- it's good.) So fuses were good, and I even swapped relays for the Auto Shutdown Relay, wondering if that could cause no signal to the coil. Still nothing. Because it is so easy to check on a Jeep, I checked another thing that may cause a no start, no spark condition: the Crank Position Sensor. On the rear top of the engine, right above the end of the intake manifold, is the three wire electrical connector for the CPS. To check the sensor, pull the connector apart, and on the sensor side of the connector, check for continuity (with an ohmmeter) between terminals B and C (marked on the connector-although mine weren't). There should be no continuity. That's the only test given for the Jeep's Crank Position Sensor.
Well, in my case it turned out to be a badly mangled pick-up coil assembly inside the distributor. That helps the computer determine crankshaft position and adjust spark timing. You need to start as I did with checking for power to the coil. If you have power there on the green wire with the key on, then start by checking the coil-it can be tested, then check the ignition control module-test it at a parts store, next check the two sensors -CPS and the pick-up coil (on earlier models was referred to as the cam position sensor). The distributor is a pain to remove and install, if you have to.. You may need to consult a repair manual for proper installation. I hope you find your problem. One last tidbit: this is my son's second Jeep he bought with the motor mount on the passenger side (right by the distributor) missing all the bolts for the mount's bracket onto the engine block. It made the engine sag to that side, and may have bumped the distributor housing hard enough to destroy his pickup coil. So do check your engine mount on that side.od luck.
May 20, 2012 |
1996 Jeep Grand Cherokee