Re: question about yamaha motor
I'm not an expert on eng but if I was you check lower unit: take out lower plug and see if you any big pices of metal. check if oil is light brown (it means water is comming into gear area). For sure check compression. Then check if battery is getting charge ( charge is lower than 12 vol it means you have a bad coil.) check every cilinder has spark. And finally the gas and oil system: check if external oil pump is working (to do this there is a emergency switch close to internal oil tank, with ignition on, press switch) and finally gas: to do this test you have to run the boat. Run it in hight look for for rpm suddenly go down (means hight pressure pump problem ) them bring speed to idle speed low rpm and motice if turn off eans low pressure pump problem) and the most important remove computer cover and check for any crack and burning areas on it ( if you see any it wll ment bad computer $600 up) that's what I wll check
