Jeep won't start, no spark

[wildman]

About a week ago I hopped in my '89 XJ and tried to crank it up and it would just sit there and turn. after tryin a few times to start it, i gave up and called someone to pick me up. i came back a couple hours later and tried again and it started up on the second crank. well, i drove it home, and now it's in the driveway dead. it turns and turns and turns but to no avail. there is no spark coming from the coil wire so i tested the ignition coil out and it works fine (gives me the same ohm reading as a brand new one). I guess that leaves a pretty broad spectrum as to what the prob could be. I'd appreciate any help. ask all the questions you need to, i'll answer as best as i can.

 

[usmc_1371]

sounds like clasic signs of a bad CPS sensor, no spark and then you have spark or feels like it is cutting out while driving. do a serch for cps sensor and you should find a ton of info. It is a good place to start.

 

[wildman]

that's pretty much what i had in mind...when i called autozone they looked it up and the guy said it rang up as an unnecessary part (don't see how it could be unnecessary). they said its a pickup coil i'm looking for in the distributor. come to think of it, it has cut out on my once or twice while driving in the last month or 2. how can i check it to see if that's the prob?

 

[wildman]

Well, I separated the connection at the distributor and ran a voltmeter on it. When seperated, the female connection (the wire running away from the distributor) got a 5 volt reading. Haynes' Manual says this is correct IF the two are connected. However, when they are connected, I get no voltage. Is this the Camshaft Position Sensor that I'm connecting/disconnecting? If so I'm assuming this will need replacing. Is this connection changeable without pulling the distributor? I mean, the connection is near(maybe on?) the pulse ring, and that ain't movin!

 

[wildman]

sounds like clasic signs of a bad CPS sensor, start.

when you say CPS, do you mean CKP = crankshaft position sensor, or CMP = camshaft position sensor?

 

[rsalemi]

Crankshaft position sensor - is 95% of the time the problem on early 4.0's. Auto Zone may not carry it - you may need to get it from the dealer, It is located at 10 oclock on the bellhousing - behind the intake manifols and the connector comes up the baco and connects to the wiring harness near the temp sensor.

 

[wildman]

cool, got the sensor from the dealer for $25 (my old lady works there, gets a HUGE discount) ;-) anywho, changed it, still wouldn't start, took the distributor apart, cleaned it and whatnot. grabbed the camshaft sensor off a junked jeep (cuz it was free, just to test) swapped it with my old one, worked fine with and cranked right up. decided to buy a brand new one from the dealer for $42 (yet another discount) put it on, and headed out. trashed my old cam sensor, kept the one from the junkyard, kept my old cps for a spare, cuz i hear they go out.....alot. thanks alot guys for the help! now, to just find someone willing to wheel on a monday night...been broke down for 2 days, gotta re-break her in! thanks again!

 

[Stoney]

when you say CPS, do you mean CKP = crankshaft position sensor, or CMP = camshaft position sensor?

nope i am pretty sure he means CPS Crank Positioning Sensor.
pretty sure that what the dealer calls it!!

stoney

 

[MJR]

It is also refered to as a engine speed sensor.

 

[wildman]

nope i am pretty sure he means CPS Crank Positioning Sensor.
pretty sure that what the dealer calls it!!

stoney

Yeah, I believe the Chilton/Haynes manuals refer to them as CKP and CMP Sensors. I was pretty sure I knew what he was talking about, just looking for clarification.