MSD Run ON ZZ4
01-25-2004, 05:55 PM
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MSD Run ON ZZ4
I installeda ZZ$ in my 74 along with MSD 6AL ignition. When I turn the key off, the engine keeps running and I had to pull out thge coil wire to stop the engine. Temporarily, I have installed a switch in the control wire wire to the the MSD. I used the old hot lead to the coil as my control lead to the MSD. I'm sure almost everyone that has installed an MSD had had this problem. MSD recommends installing a diode in the Alernator control wire BUT they say thsi is because of the bleed through from that wire through the GEN light to the control wire BUT we do not have a GEN light. We have a gauge. Just curious what others have done to correct this problem. Thanks
01-25-2004, 08:05 PM
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Re: MSD Run ON ZZ4 (marioncole)
I did not have that problem with my car, but it could be something with your wiring. Have you double checked all the wiring in the car?
01-26-2004, 02:29 PM
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Re: MSD Run ON ZZ4 (Sigforty)
Please advise did you have run on or not with MSD. I would appreciate hearing from thoese that had no problem. That would lead me to believe I have a wiring problem somewhere. If I pull out the fuse for the gauges, the engine will turn off when I turn the ignition key to Off but if I do not pull that fusse, The msd receives enough voltage from the control wire to keep the MSD supplying spark to the engine.
01-26-2004, 02:45 PM
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Safety Car
Re: MSD Run ON ZZ4 (marioncole)
I do not have that problem but my year uses an ammeter rather than a volt meter. Depends on what instrument your car uses. A volt meter is the same, circuit wise, as an GEN gauge. None the less, the diode will fix that problem.
01-26-2004, 02:59 PM
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Re: MSD Run ON ZZ4 (gerry72)
I remember seeing an article in Hotrod or Carcraft where they put a ZZ4 in an 70 series car and it continued to run after the key was turned off. I think they installed a diode inline with the alt. The coil was getting feedback through the alt causing the car to run after the key was off. Good luck.
01-26-2004, 03:54 PM
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Re: MSD Run ON ZZ4 (marioncole)
I have the same ZZ4 and MSD as you, but in a 78. I think it's in your wiring. I don't have any shut off problems. I just have a skip at around 4000 rpm. Good luck with your wires
