have a 1985 115 Yamaha that runs fine for about 13 minutes and then shuts down. Very little warning. Wait about 3 to 4 minutes, starts up and runs for about 6 minutes, shuts down again. At the suggestion of an Outboard Mechanic I have:
Drained fuel and replaced fuel lines, filters, and connections. Both tanks.
Lower unit was getting water in oil, so I changed water pump and seals in lower unit.
Gasket between motor and lower unit was leaking, changed that and flushed out all water channels.
Changed thermostat gaskets and took out thermostats, South Louisiana, he felt there wasn't a need.
Changed fuel pump.
Test fire and reset spark plugs.
He checked Stator and he feels they are in good shape.
He suggest that I change ignition pack