Home Forum Ask A Member 1940 mercury k4 no spark both cylinders

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  • #165304
    benji41
    Participant

      US Member

      Had running two weeks ago now will not start. After checking I have no spark. What will cause both cylinders to not spark.

      Jim Benjamin

      #165305
      dave-bernard
      Participant

        US Member

        was the mag gone through ? condensers dirty points. leaking top seal that fouled the points.

        #165306
        benji41
        Participant

          US Member

          Yes points look good and set at .018 ,condensers check ok with multi meter, coils look good and all connections are good and tight. Do not have coil tester.

          Jim Benjamin

          #165311
          jeff-register
          Participant

            US Member - 2 Years

            Had a problem with a 200 misfiring & needed to run a ground wire from the mag plate to the block to bond.
            Also check the resistance on the coil spark plug wire, both, to ground (mag plate) & let us know what readings you have
            please,

            • This reply was modified 5 years, 3 months ago by jeff-register.
            #165354
            billw
            Participant

              US Member - 2 Years

              Disconnect wires from points. Use an ohm meter set at low ohms scale and check that resistance goes from infinity to zero across the points, when the points close. Not two ohms, not one ohm….zero. Points can look great but not make the proper connection. If this test fails, you’ll have to clean the points. If this test is passes, then put the meter on high ohms scale and check that the reading is infinity with the points OPEN. You’re looking for a high-ohm short to ground, through the point assembly.

              I would also be willing to bet money that, if the condensers are original, they will not pass a leakage test. This does require a dedicated magneto analyzer to test properly. It’s just as easy for a regular guy to get new condensers.

              Long live American manufacturing!

              • This reply was modified 5 years, 3 months ago by billw.
              #165640
              jeff-register
              Participant

                US Member - 2 Years
                • This reply was modified 5 years, 3 months ago by jeff-register.
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