sounds like you may NOT have the wiring correct, there should be a bypass wire [starter to ignition sw to coil OR output end of resistor] that's only 'hot' when the starter is engaged, and a 2nd hot wire to the ignition switch that feeds the input end of the resistor when the key is on [
brown wire here] - the symptoms say you're missing that 2nd connection somewhere along the route, the coil fried because it's getting full 12V all the time
Bill
