1990 Jeep Comanche sport, randomly won’t start

[90manche]

I got a 1990 Jeep Comanche sport with the 4liter in-line 6, I have had it for 3 weeks and in the time I have had it, it had randomly decided not to start 3 times. It will still crank, just not actually start, but I can bump start it fine, and if I wait 30 min or so it will start again, any ideas?

[eaglescout526]

Sounds like CPS. Cruise has testing procedures on this to root out a bad CPS 

[NHMJXJ]

  Crank Position Sensor.  That's how it begins … then one day you'll be driving along and it will stop running all together.

[90manche]

That’s what I was thinking it was, from what I’ve found. What is the easiest way to change that?

[eaglescout526]

The CPS? There’s only one way to change it. You have to unbolt the two bolts holding the sensor in place on the drivers side of the bell house and then unplug it from the engine side. Be careful not to drop the bolts down into the housing. A decent length extension and an 11mm socket should take the bolts out. 

[JustEmptyEveryPocket]

I have gorilla sized arms and sausage sized fingers. For me I have to take the transmission crossmember and exhaust pipe loose and let everything hang down (supported by a jack stand) to be able to reach it. But don't trust me. If there is an easy way and a hard way to do a job I choose the extra hard way of doing it, every time.

[JMO413]

32 minutes ago, 90manche said:

That’s what I was thinking it was, from what I’ve found. What is the easiest way to change that?

http://cruiser54.com/?p=50

Here's cruisers CPS test.

 

I have changed a couple. Get a nice array of extensions. Some long some really long and couple shorts. Get a good swivel then figure the combination to reach the bolts. When you are going back together black tape on the socket to hold the bolts is a life changer!

[Warren Mohler]

if it's the first time being replaced you may find a hard rubber plug around it to keep trash out of bell sort of a pain in the butt, it will keep mice, bolts etc. out 

[90manche]

Thanks for the help! I will plan on changing that ASAP 

[EvilMJ]

My 89 did this to me twice recently in a period of 4 days.  I replaced coil to no advantage, but replaced the ignition control module underneath (seemed fine when pulled), and have not had a problem since (been about a month and 1k miles).  I will say, during troubleshooting, I had no spark from distributor or coil - hense my belief it was the coil or ICM.

[Drahcir495]

On 12/24/2019 at 12:34 PM, JMO413 said:

When you are going back together black tape on the socket to hold the bolts is a life changer!

Was going to say that. Just awesome advice