Over heating problem??

[Louis Evans]

I have a 1989 Evinrude 70 hp that continues to go into the S.L.O.W mode after running down the lake after 10-15 min. I can't figure what else I can do to correct the problem.
I have replace the thermostat , disconnected the VRO pump, I premix oil and gas, replaced temp. sensor, replaced the water pump. The warning horn is not working at all. If I put 12 volts directly to it ,it sounds. Is it a bad wire that is causing my problems?

[boats.net]

Check temp sensors and check engine temp with infra red thermometer to what temp it is when overheat is activated.