[SeanF]

Does anyone know what the general fuel consumption is for a Mercury mariner 150 Magnum II outboard at various engine speeds?

I'm trying to calculate optimal fuel efficiency and I know MPH at various engine speeds but I don't have good data for GPH

Thanks.

[DRIFTER_016]

As a general rule, you will get your best fuel mileage between 3500 and 4000 RPM.

[SeanF]

Thanks. Any Idea how I can quantify that? I'm trying to get a handle on maximum cruising range, so I'd like specific GPH numbers, if possible.

Thanks again.

[Tregaskis]

Generally, a carbureted 2 stroke burns about 1 gallon per hour for every 10 horse power generated. That means at full throttle, your 150 horse Mariner will burn 'in the neighborhood' of 15 gallons per hour. You dont say your boat size, weight, prop pitch, etc so estimating the power needed at various speeds is impossible.
Best fuel mileage usally occurs between 3500 and 4000 rpm on these engines, assuming you are propped correctly tp allow the engine to run to rated rpms (probably 5800 rpm on this engine).