30hp yamaha 3cyl loss power

[Russell J]

I have a '96, yamaha 30hp long shaft on a 14'6" polaris inflatable soft bottom, it weighs about 500lbs. I'm having a problem. Bought it used from a very detailed and tidy owner. He stored the boat in a carpeted garage!! It was stored over the past year and he did put a teaspoon of oil in each cylinder to keep the rings in good shape. my problem is it runs rough at low rpms and it has no power under any load. It can get up on plain and that's it. Here's what I've done so far;<br />new gas, spark plugs, and a carb cleaning and compression test show excellent. the filter looks clean and there's no air in the oil line. I've let it idle for over an hour to burn off any oil in the carb. <br />any advice would be appreciated.

 

[masteroutv]

Re: 30hp yamaha 3cyl loss power

You said that you put new gas in it. If there was gas left in the tank by the previous owner for several months then the gas may have laquered. My dad had this problem last year and after replacing the gas in the tank it still took him most of the summer season to run the bad gas out of the engine. You might try adding some type of fuel conditioner.

 

[jim dozier]

Re: 30hp yamaha 3cyl loss power

More on the bad gas. Your initial description sounds like a standard case of gummy carbs from sitting too long. How exactly (in detail) did you clean the carbs?<br /><br />PS I wouldn't let it idle for an hour. That just going to carbon up the plugs. Also until you figure out what's wrong you might be running lean which can be hard on the engine.