Re: 1981 Evinrude 9.9hp 2str starts but won't run
"A shot of ether after it dies does not bring it back, only time will fix it. That says 'flooded engine' to me, but I write software and have very delicate hands."
A plug reading should tell the story. If it is black and wet it is likely flooding and fouling the plug. Does a new plug help at all? If it is dry it is likely not enough fuel is being delivered. If it runs at all the spark is probably OK. I think solid state ignitions either work or not, not much in between?
I had the same motor, 15HP, bigger carb, I think, for 10 years. Many, many hours of hard running for hours on end. Treated it to new plugs once a year, changed the gear oil once in a while and that was it. It was still running perfectly when I sold the boat. Assumming the compression and seals are OK your motor should be OK, once you get the bugs out.