Evinrude overheat alarm

[boatymcboatfayce]

Hi all, was looking for a little assistance with this. I have a 98 150 oceanpro. She will alarm and limp mode ONLY around 2300 rpm. Wot no problem. 2k rpm fine. That rpm is when the boat is plowing and will fire that overheat alarm. Neutral and refire and it's fine. Water pump and thermostats are new. Telltale is always visible and strong during this episode. I heard that fuel issue can trigger that alarm. I have gone through all 6 plastic carbs. Replaced needle and seats. Adjusted floats and cleaned them. They are simple lawnboy carbs for all my 2 stroke guys out there. This boat did have a fuel separator that was removed. I installed a new one just because. I never replaced the temp sensors as I felt that they would act up at different rpm and not just this rpm range. I guess my question is do these motors have poppet valves? I never remember seeing any. Any thoughts for me? I have not pulled the heads as I think salt would be more restricted at wot. Thanks in advance.

 

[brodmann]

Sounds pretty odd. Id pull the temperature sensors and put them in a pot of water with a thermometer and an ohm meter connected to the leads. Basically, the sensor will have continuity at a certain temperature. I'd check them one at a time, unless you have 2 ohm meters laying around. I have no idea what type of carburetor problem would cause this problem. I've had a motor that would set the alarm at idle and a couple that would sound the alarm at WOT, but never have heard of what you have going on.

 

[boatymcboatfayce]

I will definitely try that. At what temp will the meter show open?