No Spark!

I have a 1990 Comanche- 4.0L I6 with a manual tranny (125k).

Last weekend, I went to start up my jeep and the engine would only crank- no spark. I switched relays, checked for moisture and cracks in the distributor, pulled fuses, and changed ig coil. This is killing me! Everything seems to check out with a voltmeter. Any suggestions?

Does my Comanche have the check engine light code flasher like other Mopars?

Please help as I am questioning the purchase of my first Jeep!

PRLJEEP

CPS

Try a crank position sensor, they often are the culprit of no spark. Oh and take your ignition module over to the parts store and have it checked out first (that's free).

Could be the crank position sensor is bad. Normally it will be that or the coil which causes a no spark situation.

Jes

I´ve heard tell (never tried it myself) that unplugging/ and plugging the CPS back in, will sometimes help with a no start. Had the plug fall off my MAP senor, stopped the motor fast, no spark.
No spark has usually truned outto be a loose or moisture filled connector someplace. I usually start by testing the (large) Yellow wire at my coil. And work upstream or down from there. Pretty sure the power cable to your coil is still yellow in the 90. The smaller yellow wire is the trigger, which will pulse when trying to start.

The crank position sensor is usually the problem. It is located at the 11 oclock position on the bellhousing on drivers side. Follow the wires up to the connector near the last fuel injector. It is a three wire connector with only two wires - red and white. Here is some info I have posted in the past.


If on a crank but no start the unplug and replug of the cps wire harness connector gets you going you may just have a wire harness connector going bad and may not need to replace the cps sensor. Here is how to test on pre 91 models: hook volt meter to both wires from cps sensor w. harness unplugged. Set the range on meter to less than one volt. Crank engine and if cps generates .5 to .8 or more volts it is ok and your connectors need tightening or replacing. I got my parts for a couple of $ at pepboy but advanceauto.com also has them. They were made my Dorman under the Motormite Conductite tech grad name # 85303, 85304 and 85305. There are about 5 pieces in each box. You can also get a small tool set that helps on the install number 85360. I fixed my 89 this way a couple of months ago when I got tired of unplugging and replugging the connector every few weeks. My cps was only 1 yr old so the engine side harness connector part was worn out. I replaced both the female and male side internals of the connectors and it not only starts every time but the idle was also improved. Greg