Small Engines (Lawn Mowers, etc.): Starting problem JD ride on, briggs and stratton, safety switch

Question
Have a John Deere 1971 Model 112 with coil and points ride on tractor that will only run when you have the starter engaged Once motor starts and you let key go to run motor stops. New switch installed

Answer
Does this have a Kohler or a Briggs and Stratton Engine on it? I would say you have a safety switch that is causing your problem.  Disconnect the ground wire to the coil and see if the engine continues to run.  The ground wire is the black wire that attaches to the coil from the key switch.

If the engine runs with this wire disconnected, its definitely some safety switch or tractor wiring issue.  Look for a switch on the Transmission (for neutral) clutch, blade engagement, or possibly even the seat.

HTH

Dave