12 HP L head twin Briggs 404707 1205 01 Won't start unless you ground one spark plug wire. Put on new coil, same problem?? : Both plug wires on, no spark. Grounded one by accident ( while checking for spark) and engine fired up on other cylinder. Engine runs great once you get it to start. Why would grounding out one side of the coil cause other side of coil to fire. Three different coils tried. All wires checked nothing else grounded out.

Well, if the wire is grounded, you should not have any fire.

Coil shut down wire is not grounded. With engine spinning at over 300 RPM no spark. Touch one spark plug wire to ground and I get spark at the other spark plug wire. Engine will then start on one cylinder. Now hook up grounded spark plug wire to spark plug and second cylinder will fire up. With both spark plug wires hooked up engine will not start!!