Yamaha fuel consumption

[Keven]

I have '98 yamie on a Cobia 184 of the same year. They were paired together from the dealer as they typically are today. I was hoping I could do something to improve my mileage. From the reports I've read, I should be getting close to 4mpg. This past weekend I was about 2 mpg or less with 2 of us in the boat. Not alot of time idling nor trolling but running 22mph to 32 mph to stop and fish here and there. It has new plugs this spring and I run 93 octane, A friend suggested I check the O2 sensor. I've never heard of one in a two stroke. Any Ideas how I can improve the mileage ?
Thank you

 

[Ray Neudecker]

Re: Yamaha fuel consumption

Please give the model number for more info on maintence suggestions that might help. I really don't expect 4mpg efficency, but also not sure of why you are not running the 87 octane fuel the engine was designed to run on.

 

[Keven]

Re: Yamaha fuel consumption

Ray,
It is a 115 F , 4 cyl two stroke, with carbs and oil injection. Saltwater series.

Thank you

 

[Silvertip]

Re: Yamaha fuel consumption

The"rough" rule of thumb for fuel consumption on any engine (2-stroke or 4-stroke) is to put a decimal point one position left in the horsepower rating. Your 115 would then "roughly" burn 11.5 gallons of fuel per hour at wide open throttle. If you estimate 2 MPG then at a burn rate of 11.5 gallons per hour that equates to 23 MPH. That means your fuel consumption is normal. Size of boat, type of hull, load, current, wind, and other factors will ultimately contribute to how much fuel any engine will consume. You can't magically increase fuel economy in any significant numbers. Get on plane and throttle back. Four strokes will burn less fuel if run at moderate speeds. Thats the best you can do.

 

[Keven]

Re: Yamaha fuel consumption

Interesting point of view. Thanks for the info.