Stan6406

Driving down the road and it just shuts off.
has fuel but no spark from the coil
I can hear the fuel pump kick on when I cycle the key.
I've changed the coil (4 times) and the box underneath it
If it cools down for a few hours it will start and run 10-15 minutes then dies again. I've checked the fusible links and they all seem good.
Any ideas ?

TimothyRaymond85

I imagine they have ignition modules somewhere im not really familar with the cherokee ignition system yet. But it sounds like a module problem.

Stan6406

I'm guessing thats the box under the coil

je4reyk

It kind of sounds like the crank sensor (cps) I have heard that act that way.

Stan6406

I thought the CPS shut off the fuel also when it went bad. I can hear the fuel pump start up just no spark.

Abovetimberline

the icm is under the coil on 87s,the cps will cause this,when it gets warm resistance will increase and cause this pronlem. Check it when it is cold and see what the resistance is and once it gets warm,see if they change.

Darnthorny

Sounds like what mine was doing right after I got it. It would die, but then start back up, or take a bit.. everything else seemed normal. Search "crankshaft position sensor". Mines a '93.. maybe an '87 is completely different.

Stan6406

We talking checking the CPS resistance? its only a few years old (not that it matters). I was just under the assumption when it went bad it would shut the fuel and spark off at the same time as it did the first time when it went bad. Or is the module more sensitive to a resistance change in the CPS then the fuel system?

builtnotbought89'

This was happening to my 89 & I disconnected the icm from the bcm (body control module, located on the passenger side wheel well)! U don't have spark while its hot after it dies, so diconect the wire on the bcm coming from the icm. Now crank it over & when it starts plug it back in! This has happened to me once or twice I think its just how u reset the icm!!!

Abovetimberline

The cps is for timing and injector pulse width,when you turn your key on you will here your fuel pump,it does not know if the cps is good or bad. Once the engine turns over and the pcm does not see engine rpm it may shut down the fuel.

Stan6406

Does an 87 have a BCM ?
Will a fuel pump turn on with a bad CPS?
I think I understand
Fuel pump will turn on regardless but the injector may not work if there is no signal from the CPS ?
Next time it dies can I just check the voltage at the TBI ?

builtnotbought89'

Ya it has a bcm they didn't change much if anything from 87 to 89!

Stan6406

Took the CPS out and it was COVERED in grease. cleaned it up real good and its running fine so far

1987XJ

its the cps, mine was doing the same thing i replaced it and it hasnt stalled since

XJ_SPORT

what does the body control module look like