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  1. #1

    Default 1972 mercury 200 20hp stator coils

    I am currently diagnosing a no spark issue on a 1972 mercury 200 20hp and think i have it figured out. when i test resistant on the high speed stator coil it reads an open circuit, while the low speed reads ~180 ohms. my question is does this mean its bad or am i testing it wrong? and why is there a high and low speed stator coil? i noticed from a little googling that this may have been the only year to do it this way is it a good design?

  2. #2
    Join Date
    May 2015
    Posts
    2,317

    Default Re: 1972 mercury 200 20hp stator coils

    Get the correct specs for your ignition from CDI electronics. That motor has the Phasemaker ignition and it was used in the 20 hp for 3 yrs, longer in the smaller engines. The ignition has quirky things about it.

  3. #3
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,919

    Default Re: 1972 mercury 200 20hp stator coils

    You got yourself a problem child there!

    Those things use points to make (instead of break) the circuit, and those points see several hundred volts. The plastic points blocks tend to micro crack over time and short to ground (several hundred volts, remember). Assuming the stator is not shot, the first thing to change is those points assemblies.

    Jeff

  4. #4

    Default Re: 1972 mercury 200 20hp stator coils

    I have read about the insulator blocks and plan to replace them wither way as preventative maintenance. I was also backwards about the stator coils the low speed coil was the one that was bad, would that cause a no spark when trying to start? Also when i tested the points one set shows continuity to ground when closed and the other set shows it when open, is this normal?

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