1965 Johnson 75 Hp Magneto Ignition No Spark

I have a 1965 Johnson 75 hp magneto ignition in my shop with no spark. It was in a few weeks ago with the same problem, and I replaced the rotor with a used one I had and it worked great for a couple weeks, and then lost spark again. Owner found a tune up kit in the boat, so I installed new points, condensor and rotor, and no spark from the button on the coil. Replaced the coil with a NOS coil off ebay, and still no spark from the button. Put the old condensor back in and no spark. So all of the ignition components are new. If I put my finger on the button and spin the flywheel, I can feel spark, but not see it with a plug wire and plug. Points are set at .020, and verified they are closing properly with a continuity light. What else can I check? Thanks in advance.

Re: 1965 Johnson 75 Hp Magneto Ignition No Spark

Clean the coil laminations where they sit on the magnets in the housing. Make sure the coil isn't arcing out the end, to the housing. But you said it is a NOS...that should be good.

Double check those points. It wouldn't be the first time that new points have an invisable film of non-conductive corrosion on the contacts.

The stud that goes through the side, with coil wire on inside and points wire on outside. Take it all apart and clean all that stuff shiny bright, and put it back together, being careful that all the insulators are there and nothing is shorted to the case. That thing should have enough spark to lift you off the floor. Well, me anyway. I hate being shocked.

Re: 1965 Johnson 75 Hp Magneto Ignition No Spark

F_R said:

Clean the coil laminations where they sit on the magnets in the housing. Make sure the coil isn't arcing out the end, to the housing. But you said it is a NOS...that should be good.

Double check those points. It wouldn't be the first time that new points have an invisable film of non-conductive corrosion on the contacts.

The stud that goes through the side, with coil wire on inside and points wire on outside. Take it all apart and clean all that stuff shiny bright, and put it back together, being careful that all the insulators are there and nothing is shorted to the case. That thing should have enough spark to lift you off the floor. Well, me anyway. I hate being shocked.

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Did all that. Getting a good jolt just spinning it with my hand, but won't arc a new plug and plug wire. Think I'll put the new condensor back in.

Re: 1965 Johnson 75 Hp Magneto Ignition No Spark

Got it. Took the stud out that goes through the distributor again. There is a tiny fiber washer by the head of the screw. The ring connector from the coil was sitting between the this little fiber washer and the big fiber washer (I'm pretty sure it was that way with the old coil), and apparently not making good contact. I move the little one to the other side of the ring connector next to the other fiber washer, and now it lights up light a Christmas tree.