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Unread 08-21-2010, 05:59 PM   #1
CCRBUM
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1989 cherokee starting problems..

hey guys I'm having a problem with my cherokee starting... started a while ago with acting up once in a while... what it does and when you turn the key to start the engine it has a rough time getting going and then starts but when you let go of the key and it rolls back into the run position it shuts its self off...use to be a thing of being able to fiddle with it and it would work but now I cannot for the lift of me get it to stay on ... any ideas? I replaced the CPS and still does it.. checked most of the stuff I could think of that might have to do with it but it seems like it's gonna be in the ignition controls somewhere right? any help would be great because I gotta have it running by monday morning for work!

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Unread 08-21-2010, 06:08 PM   #2
TOWMAN35
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ing module under the coil pack that should do the trick
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Unread 08-21-2010, 06:26 PM   #3
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just to make sure this is the guy you are talking about correct? and is $107?
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Unread 08-21-2010, 06:58 PM   #4
tjwalker
It's the crank sensor!
 
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Quote:
Originally Posted by CCRBUM View Post
what it does and when you turn the key to start the engine it has a rough time getting going and then starts but when you let go of the key and it rolls back into the run position it shuts its self off!
What you describe could be the "ballast resistor". Memory doesn't serve me correctly here, but it would be either on the firewall or on the side of the engine bay. A cream colored ceramic resistor.

I would try jumpering that resistor with a small piece of wire. It is completely safe to to do this as the ballast resistor is basically there to reduce noise in the fuel pump circuit.

A bad ballast resistor will work when the key is in the START position (allow fuel), but as soon as you let off the key, it will stop fuel delivery.

It could be something else but you must eliminate the ballast resistor first. Start there.
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Unread 08-21-2010, 07:06 PM   #5
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good to know. and that sounds like it'll be a little cheaper to deal with too! I'll give it a shot in the morning and post some updates on where I'm at with the progress. thanks!
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Unread 08-22-2010, 06:48 AM   #6
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ok guys I bypassed the ballast resistor and still no fix.... for sure I'm getting a quicker and cleaner start up but again, as soon as the key falls back into the run position it cuts out. I picked up a used ignition control module from the pick and pull and it was either bad or not the problem... tried switching between it and the old one and nothing... anything else that it could be as far as cheap fixes? new parts..Coil has been replaces, crank position sensor has been replaced.. ballast resistor bypassed... ignition control module swapped out with another used one... where to next?
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Unread 08-22-2010, 06:49 AM   #7
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also is there a way i can test the ign module before I go buy a new one?
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Unread 08-22-2010, 07:02 AM   #8
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It seems to me like you have a fuel pressure issue. Have you ever tested it to see whats going on?
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Unread 08-22-2010, 07:17 AM   #9
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tested fuel pressure with ignition key in run position and there doesn't seem to be any pressure ( I didn't use a gage though) for sure there is pressure though when it is starting up.. other than the fuel pump its self what would could be the problem?
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Unread 08-22-2010, 08:48 AM   #10
tjwalker
It's the crank sensor!
 
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Try swapping the fuel pump relay with another. Located in the PDC (black box under the hood). These relays are of the same part number and can be safely swapped.

Certainly could be something else (ignition switch or ??) but simple stuff first.

Verifying fuel pressure with a gauge (before/during running of engine) may yield a clue
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Unread 08-22-2010, 11:11 AM   #11
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alright guys replaced the ignition switch and it had obviously shorted at one time.. didn't fix the problem though so I did as tjwalker had suggested and swapped relays around and that seems to have fixed it ... not sure if I can attribute the problem solely to one thing or another.. she's an old jeep and doesn't look like anyone ever took care of her! but it's running now so thanks for all the help and advice!
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Unread 08-22-2010, 12:06 PM   #12
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Quote:
Originally Posted by CCRBUM View Post
just to make sure this is the guy you are talking about correct? and is $107?
yes
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Unread 08-22-2010, 01:55 PM   #13
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Quote:
Originally Posted by CCRBUM View Post
alright guys replaced the ignition switch and it had obviously shorted at one time.. didn't fix the problem though so I did as tjwalker had suggested and swapped relays around and that seems to have fixed it ... not sure if I can attribute the problem solely to one thing or another.. she's an old jeep and doesn't look like anyone ever took care of her! but it's running now so thanks for all the help and advice!
Glad you figured it out. It seems it was the relay, right?
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