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Unread 10-08-2007, 09:12 AM   #1
maddmatt
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Location: Prospect, Pa.
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Spark? CPS?

Hello all,

My Comanche will turn over when i'm trying to start it but it will not fire up. Like it is not getting any spark. I read a few articles that you guys have posted about the crank positioning sensor, where is it located at and what does it look like? a pic would be great! Also what else should I be checking for? I have a good battery ,new plugs ,wires , cap and rotor.

Thanks,
Matt

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Unread 10-08-2007, 09:14 AM   #2
maddmatt
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It is a 1987 Jeep Comanche 4x4 with a 2.5 litter 4 cylinder.
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Unread 10-08-2007, 11:02 AM   #3
Pete M
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1988 MJ Comanche 
 
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Sorry for the bad pic, but it's all I had on the 'puter. The top one is a 2.5L.




This is a clearer shot of a 4.0L CPS, but the CPS is in a similar location on the drivers side of the bellhousing.
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Unread 10-08-2007, 05:25 PM   #4
maddmatt
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Thanks for the help!! that is exactly what I was hopeing for, now I know what and where the CPS is.
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Unread 10-10-2007, 05:32 PM   #5
Comanche5L
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Hey, if you have a hanes manual and a tester you can check the CPS before you replace it! might save a lot of work and those are not cheap. the easiest way i found was to drop/lower the tranny/tcase mount, and disengage the 4x4 linkage. then you can easily get to the two bolts. saves a lot of headaches and about a mile in extensions =P
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Unread 10-24-2007, 11:00 AM   #6
maddmatt
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I replaced the CPS and still no spark> I'm starting to hate this truck!
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Unread 10-24-2007, 10:12 PM   #7
96JXJ
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Have you checked the coil? Getting any spark from it? JIM.
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Unread 10-25-2007, 10:07 PM   #8
COMANCHE4X4
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Quote:
Originally Posted by maddmatt
Hello all,

My Comanche will turn over when i'm trying to start it but it will not fire up. Like it is not getting any spark. I read a few articles that you guys have posted about the crank positioning sensor, where is it located at and what does it look like? a pic would be great! Also what else should I be checking for? I have a good battery ,new plugs ,wires , cap and rotor.

Thanks,
Matt

You say "like its not getting any spark" did you actually test for spark, ?
maybe it was never tuned up?
could be a bad dist cap or rotor,bad coil wire or coil, broken wire. Could be you have spark and no gas, do you have gas in the tank? Are you getting the correct fuel pressure at the TB?

you need to start testing parts not just guessing the problem.
That would be you’re first things to test.
Get a repair book to help you troubleshoot and go through the steps and you will gain knowledge. Just turning the key and guessing what the problems will not do you any good. You have to test things and find the problem.
As suggested by others you need to test parts to determine if they are functioning or not before you start replacing parts that my be good, get a book to help you understand what to test and how to test and what tool to use.
Start there and work your way through.
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Unread 11-05-2007, 02:52 AM   #9
mca1977jpsnet
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Here are some common problems. CPS, Crank (on bell housing), Cam Pos. sensor (in distributor), Coil, or Coil module (sits under coil). Chilton, Haynes, or Mitchell on demand should have testing specs.
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Unread 11-05-2007, 11:26 PM   #10
carnuck
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Someone sold me the wrong CPS when I had my '86 on the road. Old one worked and new one didn't! Could also be the computer died.
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Unread 04-14-2008, 05:23 PM   #11
ddbrown
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A bad coil. mine had spark, that's when I bought a cps to no avail. the spark wasn't enough to start it.
even if it isn't you'll have a spare.
Good luck.
Dale B.
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Unread 05-19-2008, 03:07 PM   #12
phillip08
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I'm having the same problem with my 1987 Cherokee Jeep. The engine turns but does not crank. (Has brand new battery, plugs and plug wires). Our next door neighbor sometime mechanic says it's the coil, because there is NO spark? Should I go ahead and let him replace the coil? He's also not sure about this cranking sensor? Will this sensor prevent the coil and distributor from getting any spark? I just don't want to start spending lots of money on different parts. Any suggestions will be greatly appreciated. Thanks.
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Unread 05-20-2008, 12:23 AM   #13
96JXJ
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Yes, the if the CPS is bad you will not get any spark from the coil. JIM.
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Unread 05-23-2008, 09:53 PM   #14
phillip08
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Thanks Jim. Our next door "cheap" mechanic went ahead replaced the ignition coil and the Jeep still won't crank? He says now that it's probably the distributor that needs to be replaced? Apparently he is not familiar with the crankshaft position sensor?

He is an excellent mechanic, except whenever it comes to electrical problems. He says the new coil is putting out spark, but not enough to turn the distributor. Does this make any sense to you? Do you think I should go ahead and let him replace the distributor? Or at this point let somebody else replace the crankshaft sensor?

Or should I just have it towed to a garage and let the "experts" do all the testing to pinpoint the exact problem?

Thanks for help.
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Unread 05-24-2008, 03:22 PM   #15
Pete M
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Electrical stuff isn't my area of expertise, but I promise someone at the comancheclub.com/forums would be able to give you more info. I'm still leaning to a bad CPS. Also, it's certainly possible for a non-mechanic to replace the CPS.
Jeep on!
--Pete
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-88 MJ; 4.0L, ex-2wd, TJ ax15/231, 78 Ford D44 w/spool, 9" w/posi, 33" trXus MTs, custom roll-bar/bumpers/etc.
Also an 86 MJ Metric ton and 2 '90 MJs
Projects/wheelin' pics: picturetrail.com/petermontie
My email: petermontie@hotmail.com
ComancheClub.com/forums
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