2005 90hp Yamaha 2 stroke buzzer is a solid buzz after engine has been running 5 to 10 minutes on plane. has good water stream

Does the buzzer come on with the key is turned on and engine not running?

2 buzzers, too hot, no oil. I had a telltale stream but the waterpump was weak as was the poppit valve. Replacing those cleared the temp buzzer. Low Oil level in reservoirs will cause a warning also.

bill no the buzzer won,t go off when the key is turned on

OK, I am going to assume it is like a Mercury. Check your oil level sensor. You can unplug the sensor and then turn on the key. If the alarm goes away, it probably the sensor. At this point, you have a decision. Fix it right and replace the tank and sensor, or what I chose. I always fill my oil tank when I get home from a fishing trip. To be sure it was not some other problem causing the alarm, I marked my tank every inch from full to empty. I made sure the tank was full of oil. I then gauged the gas in the fuel tank and added enough oil to give a 50:1 ratio. That way the engine got enough oil if it was an oil pump failure. I ran the boat on a normal trip and then checked oil level in the tank. It had dropped about an inch and a half, which is normal for a trip to Fayette. Sure, the engine smoked a little more, but it got lube. Now, I just make sure the oil tank is full before all trips.

I don't find much information on Yahama having the sensor problem like Mercury has but I did find a few instances of sensor failure. Well, not really sensor failure but the float in the tank failure. And on my Mercury it is about $150 to replace the tank to get a new float assembly.

bill I worded my answer wrong. the buzzer does not buzz when the key is turned on

So I have a 1999 Yamaha 90. Had a very similar issue last month, I replaced the water pump a year ago. A month ago the buzzer started, had a good stream. I figured after 20 years it was probably the thermostat, (since I just replaced the water pump last year). Replaced that. Very next day buzzer went off again. Good water stream, looked at the water pump once back home, found one of the blades of the impeller was cracked and broken. Replaced impeller, so far no buzzer.

Jeff

My 2000 Yamaha has a buzzer for water in fuel / water separator. If you keep running it , it will go into limp mode, only running at little more than idle.

Your mileage may vary.
Mo