Home Forum Ask A Member 1956 Johnson 30hp Only 1 Cylinder Firing

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  • #288878

    I have made no change in the cam in 3 years and it has been working fine that entire time

    #289026

    Community:  I am at a complete loss at what next steps to pursue so resurrecting this thread a bit.  I did check that both of the sparkplugs are firing (and are both brand new).  Looking for some thoughts on next things to try to see if I can resurrect the half of the engine that isn’t working.  Any thoughts?

    Rich

    #289028
    fleetwin
    Participant

      US Member - 2 Years

      Just want to review to make sure I haven’t missed anything or misunderstood.  What you are saying is that both plugs are firing, but the engine seems to be running on only one cylinder?  If so, have you figured out which cylinder is not functioning?  I know it is tough, but a video (link would be fine as well) showing the engine misbehaving would be very helpful

      #289035

      From the earlier post it seems that the feeling was that the “dry” sparkplug was the properly functioning one and the “wet” one was the suspicious one which corresponds to the bottom chamber.  When I start the engine it sounds basically perfect – the only thing is when I get out on the water it basically travels at half speed and can never plane.

      #289036
      Buccaneer
      Participant

        US Member

        Have you tried grounding out one sparkplug at a time while it’s idling to see if it’s
        firing on both cylinders?

        Prepare to be boarded!

        #289038

        How do I do that?  Touch the sparkplug to the engine block while the engine is idling?

        #289043
        Buccaneer
        Participant

          US Member

          How do I do that?  Touch the sparkplug to the engine block while the engine is idling?

          You have to find a way to short out the plug wire while attached
          to the plug and with the engine running. If you notice a drop
          of rpms when you short a plug out, you know that cylinder is
          firing. Of course, that’s not to say it’s firing at higher rpms.

          You could pull the rubber boots off the plug wires and hook
          the plug wires back up, then you’d have easy access to ground
          the plugs.

          Prepare to be boarded!

          #289051
          labrador-guy
          Participant

            US Member - 2 Years

            How do I do that?  Touch the sparkplug to the engine block while the engine is idling?

            If you have a test light you can pierce the spark plug hood with the pointed end of the test light while the motor is running.  That will kill that plug.  If that plug that you pierce make no difference in the way you motor is running you will know that plug is not doing it’s job.

            hope this helps.

            dale

            #289054
            Buccaneer
            Participant

              US Member

              How do I do that?  Touch the sparkplug to the engine block while the engine is idling?

              If you have a test light you can pierce the spark plug hood with the pointed end of the test light while the motor is running.  That will kill that plug.  If that plug that you pierce make no difference in the way you motor is running you will know that plug is not doing it’s job.

              hope this helps.

              dale

              Just curious Dale, what does that operation do to the test light bulb?
              Don’t think I’ll try it on my new light.

              Prepare to be boarded!

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