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Ignition

Discussion in '40- & 55-Series Tech' started by Lizrd, Mar 1, 2004.

  1. Lizrd

    Lizrd

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    Subject vehicle is a 73 fj40 with 78 distributor, igniter-type. Problem: vehicle shut down yesterday, then would start back up with key in start position, but die when key was released to Run. Replaced the "igniter" coil with a new "external resistor" coil, and it runs fine. I figured bad coil, so when I got home I put in a spare igniter coil, same symptoms as before. Installed a used resistor coil, ran fine again. Voltage while running was 5 volts at the plus terminal of the coil.
    Additional symptom: checked fuses when the first incident occurred, the second from the bottom was HOT but intact.
    My thoughts: could there be an impedence problem in the fuse block that's reducing primary voltage to the coil? What should the voltage be, at the plus terminal, 73(resistor) vs 78 (igniter)? I'm thinking the 78 coil wants 12 volts, and when the voltage dropped below six it could no longer function. Also the resistor coil should get around 8 volts, I'm thinking, and thus might have a lower threshold of failure.
    I'm thinking i need to clean or replace the fuse box, and that the proper (igniter) coil would then work. Tht's a lot thinking. I tired :-\
    What do you mud gurus think?
     
  2. Rocky_LC

    Rocky_LC

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    There was some info on the old SOR Archive on this.

    If the engine runs while the key is in the start position, then dies when the key is released to the "Run" postion, the problem could be in the ballast resistor circuit. In "start" the coil gets full voltage through the starter solenoid and bypasses the ballast resistor.

    Good Luck

    Rocky
     
  3. tobydog

    tobydog

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  4. Lizrd

    Lizrd

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    I understand the above, but there is no ballast resistor. I'm running an igniter setup. I think it's possible that there's a weak ground somewhere in the ignition circuit, possibly at the fuse block, causing voltage drop thru the primary circuit. In start position, there's good current because that circuit has a different path. IMO, the voltage should be tha same, start or run, in an igniter system.
    Anyone have any experience with this?
     
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