i have a 1993 mercruiser 350 mag alpha 1 drive with a thunderbolt ingnition IV. i have no spark from coil . go and check voltage to coil no 12 volts from pos to neg on coil i check pos to a ground and i have 12 volts jump out neutral safety switch retest still same. go and crank engine while checking voltage pos to neg 0 volts pos to a ground 12 volts start trace out wiring two purple wires to pos and two grey wires on neg . one goes to tach and other goes to distributor . kinda lost on why voltage is gone i did replace the motor in the boat and everything got hooked back up no extra parts or wires rechecked all grounds all are on . can someone please help
