[seamule1]

My 2000 40hp yamaha 4 stroke recently had the alarm go off and the rpms dropped like they are supposed to. When I got home I found that the temp sensor was broken where it screws in the block (plastic fitting). I ordered a new sensor and removed the broken piece that plugs into the harness. Waiting for the new part to arrive, I took the boat out today but couldn't get past idle and the alarm went off. My question is this....does removing or unplugging the sensor still cause the alarm to go off or might there be something else causing it to go off? The tail tell is working fine and it does not overheat...I can put my hand on the block while running. Thanks for any input!

[Redneck]

seamule I don't have the answer to your question, but have the same model and year motor as you do. Have you had any problems with carbs stopping up?

[seamule1]

Yes the carbs had to be rebuilt once because it sat for 3 years without using it. After the rebuild I installed an inline fuel filter and haven't had any problems since except for now he alarm is going off.

[Redneck]

When I got mine it had been sitting for a year and half, carb job needed. Gas got contaminated again just after 6 months and had to have them cleaned again. Got rid of the old metal gas tank and went with a good plastic one. Keep an eye on your gas. That is one of the main things with yammy 4 strokes I have been told by yammy dealer, contaminated gas screwing up carbs.

[seamule1]

Along with the temp sensor, i have read a couple of threads that talk about an oil sensor and poppet valve. Do those apply to this motor as well? And can they cause the alarm to go off in the throttle control?