Reply To: 1970 4 HP, one cyl American Made Mercury

[David Stanton]

Thanks for the insight. I tested with a screwdriver held into the output tower of the coil and a test lead on the screwdriver – I can see that the screwdriver is touching the internal brass connector I’m holding it against with pressure. I removed the coil and put the other lead right on the now -exposed ground wire. I also checked the spark plug wire and continuity is great. I’m a retired electrical engineer with a lot of TV stereo repair background in a past life, so I understand making good contact and eliminating bad wires, etc. The coil secondary is open no matter how hard I try to insure a good connection, one of the green coils from the parts motor is also open, and physically damaged; and the other green one tests fine with the same test method. Can I use the green one? Otherwise I have a couple more parts motors I can dig out and see what they have for coils, but I have to move several motors to get to them. I also understand that resistance check is not a perfect test for coils because spark could be jumping inside then through bad insulation.
Dave