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Thread: 68 911L with MSD and "run on"

  1. #1
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    68 911L with MSD and "run on"

    Hi Guys
    Still have ignition issues. Using L59 wiring diagram with MSD 6 AL. Missing the 8 Resistor. Engine starts and runs smoothly but will not shut off with key. MSD says to use a dual ballast resistor connected to the small red wire of MSD and connected a switched 12v. I have done that and also tried diodes that MSD recommends for Ford and Chev. Is the missing NO 8 resistor a problem? Engine will su

    Has anybody had this problem?

  2. #2
    I have the same issue with twin MSD 6AL. I have a set of kill switches wired to them to shut off the motor but I'd love to trace the actual gremlin down.

  3. #3
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    The way I stop the engine is to unplug the small MSD wire. Does the starting relay fail with age? The way we all do! I do not have a connection to no 87 on the relay. Any help is appreciated.

  4. #4
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    Actually, can I power the MSD little red wire with the blue wire that powers the alt light, since the alt light goes out when I turn the key off??? Could it actually be that simple?

  5. #5
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    Since the alternator light also goes out when the engine starts, That probably won’t work. Have the same MSD on my car and love it! Have you checked the small red wire for voltage when the ignition is off. Sounds like your “switched 12v” is not really switched, but has power all the time. The power to the fuel pump is switched, you could jump from that to the msd wire and see if that stops the “run on”

  6. #6
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    Thanks I will try that

  7. #7
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    The blue wire does not have 12 volts until the alternator is producing 12 volts , so will not work for the MSD .

  8. #8
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    Some success.
    I no longer have "run on", but now my tach does not work??
    I believe the Starting relay was my problem. Now the connections are: 85 ground, 86 switched 12v, 30 bat 12v, and 87 to a 4 post ballast resistor suggested by MSD techs. Motor runs and stops with the key.
    Now the tach is an issue? I have the MSD tach adapter but the B/P wire is not connected and the MSD tach connection does not work. Can I power the tach wire (B/P) to a switched 12v?
    Any help is appreciated. Thanks

  9. #9
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    Name:  1EE8768E-3DE1-4B41-B529-4EAE0CC248FD.jpg
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    Here s how I wired my MSD. I converted to spade terminals, so I could go back to the regular ignition in a couple of minutes if the MSD failed. MSD has an internal fuse, so you do not need to have a fuse on the big red wire.
    Steve

  10. #10
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    Quote Originally Posted by 1969911T View Post
    Name:  1EE8768E-3DE1-4B41-B529-4EAE0CC248FD.jpg
Views: 258
Size:  121.8 KB

    Here s how I wired my MSD. I converted to spade terminals, so I could go back to the regular ignition in a couple of minutes if the MSD failed. MSD has an internal fuse, so you do not need to have a fuse on the big red wire.
    Steve
    Thanks for your input.

    Here is my current situation
    Have battery power at the rear terminal block. A bus bar fed by the stock keyed pwr harness R/W wire. The starter relay powered by bat to 30 term. Ground to 85, bus bar pwr to 86, fuel pump to 87. the yellow wire from starter to 86 will not energize the starter relay. Yellow wire has continuity from key to relay. Note: key does shut off fuel pump when engine is not running. So I assume the key switch works?

    The engine runs normally but will not shut off by key. A 4 prong resistor is in line with the "red wire" from MSD. I disconnect the red wire to stop the engine.
    Any help is appreciated.

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