2001 30hp yamaha runs poorly at full throttle

Hello

I have a 30dmho (yamaha) 2001 and i am having a problem with it. When i give full gass the motor only has half power and it coughs a lot at full rpm. It is allsow comming petrol out of the exhaust.

Now this problem happened when i was cruising at full speed then it suddenly stoppeded working at the bottom cylinder. And it wasen't before resently that i got it to work at the bottom sylindere but the engine is still not running that good at idle or at full trothle.

please come with suggestions to what the problem could be. And i need to know how to check the timing on all the cylinders:rolleyes: so i can check that.

Re: 30hp yamaha runs poorly at full throttle

After you do a compression test and confirm that you have spark at all cylinders, it's time to troubleshoot the fuel system.

I will assume that the motor is properly stored when not in use - particularly for extended periods.

Also, at 9 years old you are at least on your 3rd waterpump impeller, maybe into your 4th or 5th set of sparkplugs, you change the lower gear oil each year and ALWAYS run fresh, stablized gas.

If that's "not the case" I would suspect that you have carbon build-up that needs to be corrected and the carb(s) are probably gummed up.

Unless you fiddled with something, the timing doesn't go out on it's own.

At idle you should be at 5 deg ATDC and at full throttle, 25 deg BTDC