225hp Yamaha rpm problems

[Lwick74]

225hp Yamaha rpm problems

hello,<br />I have a 1988 225 yamaha excel motor that im having problems with. At low and medium rpm's the mootor runs fine, but at higher rpms the motor stutters. It's almost like im losing spark in a cylander for a split second then it come back. Has anyone had this kind of problem before?<br /><br />thanks,<br />Larry

 

[TONY H]

Re: 225hp Yamaha rpm problems

Re: 225hp Yamaha rpm problems

Larry, are you getting a warning buzzer when this happens? They are hard to hear sometimes.<br />Did this just start happening of did it happen since you started out the season?<br /><br />IF you started the season with it, It may be one of your carbs are a bit gummy in the jets.<br /><br />If it just started and you are getting a warning buzzer, your engine may be going into 'Limp Home Mode. Just below your oil tank (on the engine) is a Control Unit. It looks at the oil in the engine tank and the Remote tank and decides whether you have enough oil to let you run normally. If it sees a Low Oil situation, it wont let you run over 2000 RPM. It will act as you described; The control module does not let one cylinder fire in this mode, it rotates as to what cylinder it will keep from firing. It does this so you don't build up too much unused fuel in one cylinder yet it lets that cylinder cool down enough to fire on a possible no oil situation...Kinda clever.<br /><br />Where in NY are you? Long Island?

 

[Lwick74]

Re: 225hp Yamaha rpm problems

Re: 225hp Yamaha rpm problems

Hi Tony,<br /><br /> Well I dont think its an oil problem, i checked that out with my clymers book. I just bought the boat too! I spent the day going over the motor, I changed the spark plugs, fuel filter, fuel lines, and fuel bulb. Its better, the motor dosnt stutter anymore, but now it does a new thing. ( i cant win ) I can run wide open for as long as i like, no stuttering, but if i back it down a little bit, it will drop down rpm's like its supposed to, but then after a minute or less, it drops some more. When i go back to full throttle, it wont give me full throttle. When i slow down to idle and go full throttle again, i get full throttle. Im thinking it might be the fuel pump, or maybe a thermal switch, but im not sure, any ideas? Im going to figure this out! Either way I'm going out to choaler banks tommorow for fishing. Oh ya, i'm over in long beach, I keep the boat in oceanside, wheere are you from?<br /><br />Thanks,<br />Larry