1990 Evinrude 225 idle timing changed

[mark munro]

I have a 1990 Evinrude 225 VE225TXESS and the other day while pulling up to the dock it would stall at idle. After chasing a number of things I found that it would run above 1000 RPM but it would stall somewhere below that. Also on initial start the auto timing advance would keep it running but it would stall when it reset. Timing at around 1000-1500 was 8 degrees ATDC and as the idle was dropped the timing went as far as 14 degrees ATDC. There seemed to be some slight back firing through the carbs on fast idle like the timing was off. I inspected all the linkage and nothing seemed to have a catastrophic failure. I pulled the flywheel and the key was ok. I pulled the sensor coil and there appeared to be some potting material rubbed off and it settled at the base. I did the bench sensor coil test and my resistance seems to be 2.2M ohms (that’s mega ohms) between port connector D and port/starboard connector A/B/C. Port connector D to Starboard D is 230 ohms like spec’ed in the manual. There seems to be two small cracks around the outside base of the potting of the sensor coil that run for about 2” and are 180 degrees from each other. I haven’t run the on engine cranking tests of the sensor coil. What would cause a sudden timing change like this? Power pack? Sensor coil? Of course after I put the whole lot back together I can’t get the damn thing to start …….