Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Hello, my name is ***** ***** I am going to assist you with this.
You sure have a weird one on your hands, but what it sounds like is that the left coil is shorting out when it gets hot, and is grounding the ignition system.
I would also have to wonder about the stop diodes in the wiring harness, as they are supposed to prevent one coil from feeding back to the other.
Was this what you wanted to know?