I just recently purchased a boat from a guy. The boat has a 1966 Johnson Seahorse V4S 80HP. When I bought the boat the guy told me the engine had no spark but the compression was good and the motor was good mechanically. He told me that it had sat for the winter and when he went to start it in spring no go. He also told me he was screwing about with the ignition wiring (sound familiar to an ad posted here a fwe days ago). Anyway I've done some tracing and here's what I found.<br /><br />Starting at the ignition switch :<br /><br />The Batt Terminal has +12v feed from the battery<br />The A Terminal has +12v when the key is on.<br />The S terminal goes to the solenoid which feeds the starter<br />There are two M terminals - one goes to ground while the other goes to the terminal which feeds the points from the coil.<br /><br />There is an electrical box at the back of the boat which houses the solenoid for the starter. One side of the solnoid is connected to the battery while the output feeds the starter. The two control terminals on the solenoid : One goes to the 'S' terminal on the ignition switch while the other goes to a safety switch. The safety switch I was told was broken so it has been removed and the wire is taped up going nowhere. <br />When I turn the key over the starter is cranking over good. I am assuming that the safety switch is so that the engine cannot be started when the engine throttle is set high. I assume the this switch will ground this terminal therefore not allowing the starter to crank when the throttle is high. (is this correct in my thinking??) I am assuming this switch is not the cause of my no spark problem but correct me if I am wrong.<br /><br />The wire that comes from the 'M" terminal is connected to the coil and the points. The other side of the coil is connected to ground. I measured the voltage on the output of the coil which directly feeds the rotor and I am only getting ~40v ac there when I am turning the engin e over. I am assuming that this coil is bad as everything else seems to check out ok. <br /><br />I am assuming that the voltage created to fire the plugs is solely created by the electromagnetic field created by the flywheel spinning belt feed. When the key is then turned off the M terminal connected to the output of the coil feeding the points is connected to the other M terminal which is ground - this cuts the ignition process.<br /><br />I am right here in my thinking??