115 Yamaha beeps

David1946

 Hi Guys..I'm new to forum because a month or so ago I bought a 2002 197 fun deck with a 1994 Yamaha 115 two stroke..Boat and motor are both awesome, except......It will get up on plane great and cruise all day at 4000 rpm but if I nail it full throttle it goes great for maybe 20 seconds and then starts beeping and cutting out..No lights come on but I don't have a overheating light...I return to idle, beeping stops and I can go to 4000 with no problems...I can full throttle from a stop and get to plane and then come back to about 4000rpms , no problem.....It pumps lots of water at idle but I have not checked at full throttle/speed...

 Thanks, Dave in Fl.

cjjjdeck

Here's something that I found on a Yamaha owners website forum that might give you an idea of what is going on.  The post is specific to 1994 115:

"The engine running at low to moderate rpm is making a certain amount of heat that is being removed by the flow of water through the cooling passages. At high RPM the engine is producing much more heat as it is working much harder and the flow of water must increase to remove the heat. So if the cooling system is not working properly and can't keep up, then the engine will overheat.

Sounds like you have partially blocked cooling passages or a bad impeller. It works good enough to keep it from overheating at lower rpm's but not at high RPM. Not unusual.

The manual will tell you how to test the thermoswitch. It may be giving you a false alarm and putting the engine into rpm reduction mode...OR it maybe working the way it is supposed to, sensing the overheat, and putting the engine into rpm reduction like it should.

The oil tank alarm is for low oil level. If the oil tank is low.....that alarm would be sounding at all RPM's. It does not know if the auto lube system is actually working or not.

If the engine is not getting enough oil mixed in with the gas at any RPM there will be no alarm, just a seized engine.

Hope that makes sense."

David1946

Great....That does make sense and I will Look at thermostat/cooling passages. The previous owner said the impeller was "new" but I don't know when???  So I will replace that also..Then I can check the thermoswitch(s).. I'm in the middle of the state so no salt water now but I don't know complete history of motor...Thanks for your answer and stay healthy...Dave