2002 Yamaha 50 HP Loss of Power and Alarms Question...

aj584211

Cadet
Joined
Aug 15, 2006
Messages
8
My 2002 2 Cycle 50 HP Yamaha purchased used on my 15" Triumph seems to be running fine 95% of the time now that I've got new plugs, gas, water sep filters, clean carbs and new fuel pump. Problem is that after running for about 15 minutes at speed (~4000 RPM's) the motor slows down and goes into "limp-home" mode. (Pee stream is still strong and oil is OK.) Then after a few minutes it picks back up.
Back at the the dock, I discovered that the alarm wires were disconnected by the previous owner. Although the motor was now OK and idling fine, when I connected the wires the alarm buzzer went off until I disconnected them again.
Two questions:
!. Are these motors subject to "vapor lock" or some other ailment that could explain the vapor lock?
2. Is there an electrical or other component that I could check/replace to get these alarms quiet until/unless there is a real problem.

Thanks a ton for any help...
Jim
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: 2002 Yamaha 50 HP Loss of Power and Alarms Question...

sounds like a high temperature problem and the previous owner may have known about it and disconnected the alarm...either dumb or dishonest or some combination. better get a new water pump impeller and probably a new thermostat also. it's good the motor is still running and hasn't been damaged by this overheating. Good Luck!
 
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