Overheating Issue

[yourmom]

Hello all, new to the forum here. Im having some trouble that I hope someone here can add some info.

I have a 1998 Johnson 20hp and I am having issue with it overheating and cant seem to find the problem. I take my boat out and can run it for around 5-10 minutes fine. After that the motor starts to stutter whenever I get past 30%-40% throttle, as if its getting and cutting the power very quickly. I narrowed down the problem by cutting the wire to the overheating sensor which resulted it in running normal (I only ran it 20-30 seconds just to verify the problem). The tell tale is flowing normal and since then I have removed the head and exhaust covers and cant find anythings that would be blocking the flow of water. It has a new impeller, water pump, power pack, all new gaskets, stator, temp sensor, thermostat (tested since and works). So I'm at a road block as to what could be the problem.

[PROUDFOX13]

Engine Overheating

Most temperature sensors work by closing the electrical circuit to GROUND when it senses a temperature at or above the normal set point, or what senses to be an over temperature condition, it generally turns on a over temp light/horn and on some engines limit the revolutions to assist in lowering engine speed and the temperature. While I do not know about your specific sensor, I would advise you to contact a Johnson dealer to verify this. If the switch is likely bad, order a new one, but do not run the engine without a switch as you may burn up the engine and a switch is new switch can be obtained from Johnson/Evinrude dealers online or at a local dealer. Get the engine model number before contacting the dealer..