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No Spark - I think

Discussion in 'Early CJ5 and CJ6 Tech' started by russo, Dec 2, 2012.

  1. Dec 2, 2012
    russo

    russo Hope is not a method

    Norris, Tennessee
    Joined:
    Oct 28, 2005
    Messages:
    498
    I parked the '5 in the driveway last Sunday and it sat there for a couple of hours. Went out later to put it in the garage, and it would not start. Lots of cranking but it will not fire.

    Spent a lot of time today looking at old threads, and this is where I think I am:

    1. There is fuel to the carb.

    2. I cannot get a spark at the plugs or the coil.

    3. resistance on the coil appears good.

    4. I get no voltage reading on the positive side of the coil - I guess this means its getting nothing out of the battery/alternator

    I am not sure where to go from here.

    Any suggestions out there?

    TNX Russ
     
  2. Dec 2, 2012
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Try hot wiring it. Connect a wire from the (+) post on the battery to the switch side of the coil. Note that it it starts, you'll have to pull the wire to stop it.

    If this works, I'd suspect the ballast resistor or the ignition switch.
     
  3. Dec 2, 2012
    russo

    russo Hope is not a method

    Norris, Tennessee
    Joined:
    Oct 28, 2005
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    498
    Thanks Tim. I hot wired it, and it fired right up. I check the switch side of the resister and have no joice there. I am guessin' that my ignition swith has gone bad. I'll tinker a little more.
     
  4. Dec 3, 2012
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    You may have other items that operate off the ign side of the switch such as radio, gen light, volt or amp meter etc. Turn the key on and observe. If they work then your switch is good and look for broken/bad connection in the wire from switch to ballast resistor.
     
  5. Dec 3, 2012
    russo

    russo Hope is not a method

    Norris, Tennessee
    Joined:
    Oct 28, 2005
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    498
    Gee Walt, and I was hopin' for a quick fix with a change in switch. This could complicate things :)The alt light does not appear to work, but all of the other lights and gages in the cluster seem to work properly. My radio is direct wired to the battery. So, it's not a good indicator.

    I still have the original 43 year old ignition switch and front portion of the wiring harness. Could be the switch or a wire. I really hope it turns out to be a switch. I would rather not take on a wiring harness right now. We'll see soon I suppose.
     
  6. Dec 4, 2012
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    After that many years on the switch, I would change it out anyways. May be the culprit. If it's not the switch then I would run an extra 12ga wire from the ign terminal to the ballast and leave the old wire in for now (simple install) and keep driving till next summers repair.
     
  7. Dec 4, 2012
    kamel

    kamel Senior Curmudgeon

    Erlanger, Kentucky
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    Jun 10, 2003
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    I would NOT replace anything unless and until it is shown to be bad. Troubleshooting this should be fairly simple.

    There were two wiring harnesses for the CJ. One was wired straight through the firewall from behind the dash and the second was wired through the firewall to a couple of connectors and then routed to wherever it was intended to go.

    So, if you have the old straight through wiring, simply jumper a wire from the IGN switch to the ballast resistor. If it starts then the original wire or its connectors is bad. If you cannot find the problem by inspectiion, simply cut the offending wire back towards the harness as far as possible and then use your jumper (following the contour and path of the wiring harness) wire and some cable ties to patch around the bad wire. I've done this with a dishwasher and the patch worked for the remaining life of the dishwasher -- about 6 years.

    If you have the 'connector' type harness and the jumper trick works, then I'd immediately suspect the connector as being dirty or corroded. A little time and some emery cloth can clean the connector pins up easily.

    Note that since your ALT light does not work AND since that wire runs through the same connector as the ignition wire, then the connector is doubly suspect as being the offending part.
     
    Last edited: Dec 4, 2012
  8. Dec 9, 2012
    russo

    russo Hope is not a method

    Norris, Tennessee
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    Thanks to everyone for the advice. It was a bad ignition switch. Installed a new one today, and it is running like a champ.
     
  9. Dec 9, 2012
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    Glad you got her going with no fuss no muss.
     

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