1987 Jeep Cherokee not starting, intermittent

[riverqueen]

Hi everyone. I need help. I just brought my Jeep back from the mechanics and after turning her off, she wouldn't start back up until about 5 minutes later. She turns, but does not crank up. This is what I took her in for! They did this:
Cleaned throttle body plates
new plugs, battery cable, fuel filter, O2 sensor

It is intermittent--they said she started for them every time. The beginning of all the trouble was a few weeks ago when I started her, she ran REALLY rough and I drove her few a few minutes (although I couldn't really accellerate) before she died while I was driving her. Since then, every so often she won't start, although it seems to be getting worse. She died on me while driving one other time, and then I couldn't start her.
Sorry this is so long winded--I've studied my Haynes manual and wonder about the:
TPS Sensor
Ignition coil
Idle Air COntrol Valve?
Also, I had my (new) battery checked and starter checked-all okay.

She's got around 225,000 miles and is 4wd

Please help if you can. I just spent $350 at the mechanics...

[fredjacksonsan]

Sounds like crankshaft position sensor. Do a search here and you'll find plenty of posts about it.

6k

[riverqueen]

I (well, okay, my fiance) looked for the CPS but CANNOT find it. I read your post on replacing the CPS, but since my Jeep is an 87, is it in the same place? Does this not go out entirely? There doesn't seem to be much rhyme or reason as to when it will not start or when it stalls. I've tried it hot, cold, etc. I can drive it for five minutes, turn it off, and then it won't start. Then I can drive it for 15 minutes and it starts right up. Also, neither my Chiltons nor my Haynes mention a CPS for my year model.
Any more suggestions? Thanks in advance

[fredjacksonsan]

I'm not sure if it's in the same spot or not, but everything I've seen indicates it should be in about the same place, about 11 oclock on the bell housing when viewed from the driver's seat. It IS hard to spot.....

[riverqueen]

I've figured out that my Haynes is calling the CPS a Top dead center switch-- I didn't know theye were they same thing. Now I have a diagram to go by-- and best of all I found a brand new one (Chrysler genuine part) in a box of parts that I got with the jeep! Thanks for all your input!
Let's hope this fixes her problem.

[longfellow]

Ignition module could be wacky also. Sometimes these will only let vehicle start cold. Yet when vehicle gets warm' it will stall. After vehicle sits awhile then it will start. Just a thought if this applies to your vehicle.

[bobv872dr]

hi riverqueen wondering how you made out with the crank position sensor. I got a 87 jeep in the family that is giving me intermitent trouble as well. I've got 3 jeeps the 87 my son a 94 gc my wife and a 96 gc v8 my daughter. Had the crank position semsor problem on both gc and fuel pump problems on all three. Replaced the crank position sensor on the 87 hoping it would solve the intermitent crank but no start and sometimes die while running problem but this was not the problem. Thinking it might be in a bad ignition switch

[Stick89]

Most probable critical problems with 87'-89'(to the best of my knowledge)
Turns over but no start:
CPS
COIL
IGNITION MODULE
ECM
Will not turn over at all
DEAD BATTERY
BAD STARTER
KEYED CYLINDER
IGNITION SWITCH
If I can remember anymore I will post back up here