I know the coil is a transformer..The spark coming out of the secondary jumps to the same black wire ground that the negative end of the primary is connected to...Yes, it is theoretically possible, if the spark plugs were inslulated from the cylinder and grounded to the circuit..Without this ground the spark jumps to the closest spot, the little black wire on the hall sensor...Or if the hall sensor is far enough away the spark jumps to the primary on the surface of the coil or down inside the insulation somewhere...
I think we're saying the same thing in different ways...
Hey TKG, how does the spark jump across the gap if there is no ground to the engine ? Air is a pretty good insulator
Somewhere along the line the engine gets connected to the negative side of the battery...