Re: 1992 Johnson 225 hp V6
It COULD be the rectifier yes. To test simply disconnect the yellow wires from the stator to the rectifier and retest. If the engine now fires, replace the rectifier.
More likely though as mentioned is the kill circuit having a possible fault. Disconnect the black/yellow wire at your power pack and re test the spark. If you now have spark, you will have to narrow it down to the key switch, shift switch, or wiring in the harness somewhere. Look for nicks or cuts in that black/yellow wire that could be shorting out.
If it gets deeper than this let us know so we can troubleshoot further.
