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Thread: CJ3A Direct Short Battery to Block: Ignition Issues

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  1. #1
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    CJ3A Direct Short Battery to Block: Ignition Issues

    Good Morning,
    My name is Chris and over the past ten months Iíve been doing a frame off restoration of a í51 CJ3A (serial 451-GB1 23480) with the help of the forum as a reference. Iíve now re-assembled the Willyís with your help and had the Jeep running with good power and acceleration.

    A month ago, my original 6V foot actuated starter finally gave up. I was replacing it with an IMI High Torque IMI-134-002 when I accidently bridged the High Voltage + terminal of the starter to the block with a socket extension (ugh).

    Engine: Re-built L-134 (Compression in cylinders ranges between 100 and 110)
    Fuel Pump: Facet Posi-Flo EFP-3 (Generating 2 psi of fuel pressure)
    Carburetor: Solex 32PBIC single barrel downdraft
    Starter: IMI-134-002 Gear Reduction starter
    Distributor: Omix 12V Solid State (Kaiser Willys 923068)
    Coil: Standard Motor Products UC15T (Resistance checks OK across primary and secondary coils)
    Ignition cables: New 7mm High Temperature
    Alternator: Delco 12V 3 Wire Configuration

    Needless to say, this was the beginning of an electrical diagnostic journey which has led me to replace:

    1) Both the terminal lugs (+ and -) at the battery. The current partially melted the negative lug resulting in an intermittent ground (that was a joy to find).
    2) The ignition switch (intermittent continuity at the BAT terminal to the other posts)
    3) The original coil and distributor ignition module. (Due care)

    At this point all of my accessories (lights, horn, fuel pump, gages, dash light) all function normally again. My starter is cranking the engine nicely but it does not start with these symptoms:
    1) Plugs are wet and I can smell fuel when cranking.
    2) Iíve pulled #1 plug and have no spark.
    3) I have 11.8 Volts between the positive terminal of the coil and BAT negative when cranking.
    4) Iíve pulled the spark wire from the coil to the distributor and checked for spark to ground during crankingÖ.no spark.
    5) The resistance across the positive and negative terminals of this new coil is 3.9 ohms.
    6) Iíve checked the resistance in my spark wires and plugsÖall seem nominal.

    Iím stumped and would appreciate any suggestions you all may have to restore spark to my plugs.

    In Him,
    Chris in Spring Hill, TN

  2. #2
    Super Moderator LarrBeard's Avatar
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    "The original coil and distributor ignition module. (Due care)"

    I'd guess, in an old fashioned system, that you had a point/condenser issue. If you have an electronic distributor module, I'd be very suspicious of it.

  3. #3
    Super Moderator bmorgil's Avatar
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    I think Larry has you in the right direction. I am also wondering about the ignition module on that electronic distributor.

    When you lost the ground after the short, it is possible it caused some stray voltage to the module. Maybe LarrBeard will explain further what happens when you lose ground in a "solid state circuit".
    Last edited by bmorgil; 04-25-2023 at 06:56 AM.

  4. #4
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    I was able to replace the electronic "module" but not the inductive pickup. Could errant voltage have affected that as well? Is there any way to diagnose the function of these components?

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    Good Evening. Tonite I replaced the old distributor with a brand new distributor...regrettably, still no spark. I still have 11.8V at the coil during cranking. I'm really at a loss to know what to check/work on next to get this Jeep to start. Any suggestions?

  6. #6
    Super Moderator bmorgil's Avatar
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    Chris exactly where are you measuring 11.8V? Where are the black and red leads from the distributor hooked? What else if anything is hooked up to the coil? Is there a Tachometer wired in? Can you take a photo of the setup?
    Last edited by bmorgil; 04-28-2023 at 06:14 PM.

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    I’m measuring the coil voltage from the + pole of the coil and the negative post of my battery: 11.8V. The black lead of the distributor is connected to the negative post of the coil and the red lead is connected to the positive post of the coil. I’ll send a picture in the morning. Thanks for your help!

  8. #8
    Super Moderator bmorgil's Avatar
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    Good deal Chris. I also would like you to measure the resistance to ground from the coil body itself to the battery negative. Then disconnect the ignition module (distributor) wires from the coil. With no wires on the terminals of the coil, what is the resistance to ground between the Neg terminal of the coil and Battery Neg and the Positive terminal of the coil and battery Negative?
    Last edited by bmorgil; 04-29-2023 at 06:40 AM.

  9. #9
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    First time posting a pic here. Trying from my iPad and it looks like it just posted a thumbnail. Please let me know if you need more.

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    644B911E-5233-4FFC-8CB6-099F10552A30.jpg

    There is infinite resistance (no continuity or resistance at my meter’s 20M ohm setting) between the coil housing and battery ground. The same is true for both measurements (+ and - coil posts) to BAT - with the coil completely detached: open circuit - infinite resistance.
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