I have a 1980 25hp merc that I bought new and it has always been a touchy starter when it is cold but it would be harder to start after it warmed up. It hasn't had a lot of use the last few years and did a spark plug change and checked all the fuel filters and drained the fuel system, I took the fuel line off at the tank and put the end in a can of sea foam and primed the fuel lines and ran the motor for a few a little while to suck the sea foam into the carb and let it soak a few hours, now the only way I can get it to fire is to spray a little starting fluid in the spark plug holes and it will run for 5 seconds and quit. The plugs seem wet when you take them out but it won't fire without the staring fluid or a little gas in the cylinders. Don't have a service person close so I am looking for some ideas to try myself.
