MJ Comanche Tech. Stock & Modified. MJ (86-92)
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help comanche not starting!!!!!

Old 01-01-2016, 09:23 PM
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Default help comanche not starting!!!!!

I picked up this 1988 jeep comanche from houston brought it to san antonio. The jeep looks like it has had the wiring harness under the hood replaced along with couple other ptarts. So the jeep did not come with a key so my dad un hooked the ignithion switch and used a screw driving to flip the switch over to turn it on but nothing happened. The jeeo does not turn over "starter does not engage" and the fuel pump does not turn on either. Now with the ignition switch flipped to the on position we do have spark and if we jump the starter we can get the motor turning and by bypassing the fuel pump we can get fuel psito engine. by pouring gas down the throttle body we can get the engine to start up shortly.

does anyone know what may be wrong?????? i know its a long shot but i hope i can get this thing running some how.
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Old 01-02-2016, 04:58 AM
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possible NSS .
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Old 01-02-2016, 02:01 PM
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Originally Posted by freegdr View Post
possible NSS .


Nss what do you mean?
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Old 01-02-2016, 09:42 PM
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Neutral safety switch. He is assuming that it is an Automatic. First bet would be Crank sensor. I would replace without a doubt first.
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Old 01-03-2016, 04:05 AM
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Originally Posted by 831xj View Post
Neutral safety switch. He is assuming that it is an Automatic. First bet would be Crank sensor. I would replace without a doubt first.
It wont start thru key but it will hot wire and run breifly so its no crank sensor as per op.


"starter does not engage"
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Old 01-03-2016, 09:23 AM
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You might check Cruiser's troubleshooting guide here:
https://www.cherokeeforum.com/f51/cr...x-tips-153657/


It sounds like you're not getting 12v through your firewall so the bulkhead connector (driver's side engine bay near your brake booster) could be the culprit, as they often are on Renix era Jeeps. Sounds like you're on the right troubleshooting path.
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Old 01-04-2016, 01:03 AM
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Originally Posted by alpine.adrenaline View Post
You might check Cruiser's troubleshooting guide here:
https://www.cherokeeforum.com/f51/cr...x-tips-153657/


It sounds like you're not getting 12v through your firewall so the bulkhead connector (driver's side engine bay near your brake booster) could be the culprit, as they often are on Renix era Jeeps. Sounds like you're on the right troubleshooting path.

Oh man so my brother n law who is pretty good with tracing and wiring stuff came to help me out yesterday and we both ended up scratching our heads after awhile.... So i said lets go to junk yard find a jeep and trace those wires and take pictures! That is just what we did and we found out why the starter was not coming on! the person who owned this jeep before ended up cutting wires..... and hooked the horn wire to the ballister on the driver side fender....so now when the key is turned the starter will crank and we got fire but still have no fuel pump coming on and no fuel presure at the fuel rail.
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Old 01-04-2016, 10:36 AM
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Originally Posted by chrisquested View Post
hooked the horn wire to the ballister on the driver side fender

WTF


So... if you push your horn do you get fuel pressure?


Fuel pump is energized by an orange (with black stripe?) wire that should run to a relay in the engine compartment. The "ballast resistor" should be supplying the fuel pump with current, but it's only a current limiter to help the fuel pump be fully energized at key-on and then run quietly when the engine is running. I've removed it from every Jeep I've owned. The fuel pump relay should have 12v at ignition on and then the ECM supplies the ground to engage it.
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Old 01-04-2016, 07:49 PM
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Originally Posted by alpine.adrenaline View Post
WTF


So... if you push your horn do you get fuel pressure?


Fuel pump is energized by an orange (with black stripe?) wire that should run to a relay in the engine compartment. The "ballast resistor" should be supplying the fuel pump with current, but it's only a current limiter to help the fuel pump be fully energized at key-on and then run quietly when the engine is running. I've removed it from every Jeep I've owned. The fuel pump relay should have 12v at ignition on and then the ECM supplies the ground to engage it.

Thr orangce and black wire at the ballister one was not hooked up and one was cut. when we was at the junk yard we found how how it was suppose to be wired up. the starter wire was not conected at all and the horn wire was plugged into the ballister.

So now we need to figure out why the fuel pump is not turning on. i also dont think the injectors and spraying either because if we hook the fuel pump straight to the battery and get fuel pressure at the fuel rail the jeep still wont turn on.
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Old 03-04-2016, 05:26 PM
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Man I wish there was someone local who could help me figure this problem out.....
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Old 03-11-2016, 01:31 PM
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Ok so how do you know if the fuel pump is coming on or not?
Most common problem in the fuel pump is a rubber hose that can deteriorat over time and cause the fuel not to travel through the lines....
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