yamaha 25 autolube

[pat37]

Hi , I have recently bought a 1996 25 yamaha autolube on a 16ft fishing boat which cuts out and sounds the alarm buzzer if I run it over about half maximum revs/ speed , below half revs/speed it runs very smooth and does not appear to misfire , it will run for a long period of time at under half power without any sign of overheating or misfiring . I am not sure if problem is electrical or oil supply! can any one suggest possible cause, many thanks ,Pat

 

[Silvertip]

Re: yamaha 25 autolube

Is the water pump working? Remove the cover and feel the heads. They should be warm but not fry your skin hot. If the engine is too hot to touch there is definitely a cooling problem such as a stuck thermostat. If the tell tale stream appears weak or is not working, you need a water pump. If the oil level in the tank is dropping at the proper rate, the oiling system is working. If not, it needs to be checked. The alarm is telling you too hot or low/no oil.

 

[pat37]

Re: yamaha 25 autolube

Hi, thanks for reply I will check head temps and strengh of water stream , oil level seems to be going down at steady rate so it could be overheating problem at higher speeds as you suggest! many thanks