Overheating or bad ECM

"This is a 1996 225HP Carb mar

"This is a 1996 225HP Carb mariner outboard. After getting on plane, temp gauge will rise to 3/4 then the alarm sounds. When this happens, the ECM does not retard the ignition to 3,000 RPM?
The last time the horn sounded, I immediately went to the P-tube outlet and felt the water. It was warm, but not hot. I pulled the cowling off and checked the head temps with a laser temp sensor. The temp's ranged from 165 to 175. ?? I could touch the thermo housing and heads without being burned? I replaced the four lead electronic temp sensor and I'm still getting the same results? Could it be something in the electronic control module? Thanks WJH"

sounds like a poor water pump

sounds like a poor water pump or housing
have u checked those

Have you check your thermistor

Have you check your thermistor?

"Yes.. I have replaced thermo&

"Yes.. I have replaced thermo's and ran with out thermo's with same results. Repalced w/pump housing and pump, and poppet valve. Pulled the heads and checked water passages and replaced gaskets. Only other thing I can think is maybe water is bypassing thru the seal where the water tube goes up into the lower block. . It would not be fun to check that! A lot of work! Thanks for the input.. WJH"

I'm having the same proble

I'm having the same problem with my mariner 150. Did you fix your problem?

"Still not resolved.I have rep

"Still not resolved.I have replaced thermo's, poppet valve, w/pump impeller & housing, temp sensor, inspected head passages and repalced head gaskets. Same result. The only thing I can think of is that at the top of the water pick up tube where it enters the bottom of the head, is cracked or the seal is bypassing. This motor has 900 hours and is ten years old. I'm repowering."

sometimes when u put the lower

sometimes when u put the lower unit on the housing seal rolls over
good luck with your re-power