JD Model M Ignition Troubles

A few months ago I posted asking for help with a JD M that a friend had that was his Dad's, and was trying to get it running again. The problem was that when he got it running, after a carb rebuild and all new ignition parts, it would run, but only for 20 minutes or so and then start backfiring and eventually die.

There was good fuel flow through the carb, so the general consensus was either the coil, or possibly the new condenser, so I had asked him to get a new set of points and condenser as a place to start, and would check for heat in the coil when we had it running again. The owner has been on a retired road trip for most of the summer, so I have not been back to the tractor. (tractor is 2 miles away, but owner is 200 miles away) I saw him in Church yesterday as he is now back for a few days, and he commented he had installed the old points and condenser back in the tractor and the tractor has now been running like it is supposed to. He drove it 4 miles around the section and it ran good. It wouldn't hardly make it a hundred yards before.

All the troubles and it was probably the new (Overseas) condenser we installed. Hard to think points as they had good spark, thus I would have to assume condenser. Thanks for all the help and comments on the tractor. Bob

What you say I have seen and heard the same many many times. Often a new out of the box condensor IS BAD. !!! Of course points being mis gappped or the fact they somehow got cleaned of oxide a bit ?? or the wiring or a prior bad connection was improved in all the happenings ?? may have also contributed to the fix??

Thanks for the feedback, now that its working dont fix it lol

John T

I was told many years ago if an engine is running reasonably well never change a condenser, they don't wear out or burn like points, and the impedance should match the coil. I have seen a few that fail like you described, just like a coil, when they get warm they stop working.