89 comanche starts but won't run

[56greaser]

My 89 comanche will start but as soon as I allow the key to come back to the run position it dies. If I hold the key over in the start position is will stay running.
I've replaced the ignition lock and cylinder as well as the ignition switch twice with no success.
Does anyone have a suggestion?
I'm going to check the crank positioning sensor tomorrow.

Thanks,

Travis

[mrbill3]

I would say it is your CPS. Post back your results.

[56greaser]

Not the CPS... any other ideas, I have no idea where to go next.

[89ltd]

is your starter relay the type that is up near the battery, or is it a relay that looks like all the rest of the relays?

[89ltd]

are we talking about the 4o.L?

[56greaser]

It's the 4.0 litre with a 5 speed manual, the starter relay is up by the battery.

[refrigerationdude]

Ignition wire? Maybe the one thats off the run terminal of the ign switch? Starter relay usually puts a full 12v to the coil, bypassing the usual ign wire, at least thats how I've seen it setup on most vehicles,. I'm not sure if thats the case w/ jeeps tho. Just a thought. I would have thought ign switch but doubt 2 are bad, thuis making me think the wiring to and from it may be fried somewhere. How do you shut the starter off to tell its staying running on its own and not w/ the assistance of the starter "helping" by cranking?

[89ltd]

I would try the b+ latch relay and also have the ignition module checked.

[89ltd]

I did some testing just now on my 89 cherokee with 4.0L. I pulled one of the wires off the fuel pump resistor ( the white square resistor located on the driver's side fender) and tried to start the jeep. It started buy dies right away. I did what you said and started it again and held the key in the start posistion and it kept on running. After some reading I found that the resistor is by-passed when you start the motor and that is why it dies in the run position. A lot of people have removed the resistor and hooked both wires together to by-pass it as it is only there to cut down on some of the wining noise from the fuel pump and is not really needed at all. I don't know if your model has the resistor so I removed the B+ latch relay and tried the same test. The engine started but would only run with the key in start position. The B+ latch relay (know on later models as the auto shut down relay) is located on the passenger side fender well. There is a row of four relays and the latch relay is the 3rd back from the fire wall. You could swap it for the a/c cut out relay for testing purposes. This link will show you the location of the relays on a 1990. Good luck and let us know how you make out.
http://autorepair.about.com/library/...s/bl920lib.htm

[56greaser]

Thanks for all the info 89ltd, I just got home from work and am going to go try this out. I'll post back with the results.

[56greaser]

turns out it was the b+ latch relay. Thanks again.

Travis

[89ltd]

Dear Greaser, thanks for reporting back as there may be many others with the same problem and now they have an answer. To many people here end up fixing there rigs and do not display the final answer, making automotive forums useless.

[ErikaS]

Hey guys I am kinda having the same problem with my 89 Jeep CHerokee... one day it worked then my hubby tried to get a window to go up when it was stuck and now it wont stay running. Mine does start in the start position too but dies when I release the key. As for checking all the relays and resistors well none of mine are where you guys ahve mentioned, there is a few on the oppisite side, seems my jeep is all turned around even the ECM is under the steering colum on her??? DO I still try all these steps you talked about?

[89ltd]

If you have an 89 cherokee they should be in the same place, on the passenger side fender well beside the coil, how ever there is a square black plastic cover over top of the relays that you will have to remove, the relays are under it.

[89ltd]

there are four relays and the one that would be the problem is the 3rd one back from the firewall. If you don''t have a/c then there will not be one in the fourth slot.