runs great, dies suddenly ?

[shawn]

   then runs again and does the same thing. sometimes starts again right away and sometimes not for a while.   

 - its my grey '86 2.5 5 spd.  it ran fine when i parked it a year and a bit ago. went to start it a couple months ago and it would not turn over. after changing the solenoid on the inner fender and one of the relays it started right up but now it is plagued with this dying issue.  I'm trying to pass it on to its new owner and a new member here. when he went to drive it home this suddenly started happening and we're both baffled as to what would cause this. it has gas in it , but now that i think about it the battery is known to be bad and won't hold a charge ( if that could have anything to do with it)  

   any and all help so greatly appreciated.  :)

[yxmj]

Check cruisers tips......probley CPS

[Jeep Driver]

It's an 86, is it carbed or TBI?

[shawn]

 throttle-body.  also, when it died, the jumper cables were still hooked up from my other truck.

[SpaghettiBatman]

Hey guys, I'm the buyer. I'm looking for cps but keeps directing me to something about child nutrition and that can't be it. If you would be so kind as to tell me what it stands for that would be swell!

[shawn]

crank shaft positioning sensor. 

 

 https://www.google.ca/webhp?sourceid=chrome-instant&rlz=1C1GGGE_enCA356&ion=1&espv=2&ie=UTF-8#q=crankshaft%20positioning%20sensor%20jeep%20cherokee

[HOrnbrod]

Crankshaft Position Sensor.

[SpaghettiBatman]

thanks

[yxmj]

It's located on the drivers side of the bell housing......you should be able to see it from the top......but you will have to access it from the bottom. 

[cruiser54]

There's some photos of it in my Tech Photos link below. 

 

Is there a ground strap from the back of the head to the firewall?

 

If so, remove the end from the firewall, clean the connector, scrape the paint off the firewall, and reattach.

 

The CPS can be TESTED. Post 7 in my Tips link below.

[shawn]

  well i threw a new cps in and did the grind and cleanup on the firewall ground. put in a good battery now  it's back to no-start, just cranks. gonna check spark asap. any chime-in appreciated. there also seems to be a short happening somewhere around the starter motor, although it still  cranks fine there have been wisps of smoke ( and thats just on relatively short cranking, like a bout   5 seconds or so ).

[shawn]

 so we've not had a chance to see if there's spark yet. hoping that will take place tomorrow. I'm now thinking that if there is spark that would indicate the ecu ( or at least the connections there-of and / or corrosion from sittting for that  1.25 yrs).  if there isn't a good spark my limited knowledge would lead me to think coil or some ignition-related thingamagig?