Merc 2 stroke fuel economy (lack of)

[Norse04]

I have a standard 1999 2 stroke 225 hp Merc pushing my 99 Proline 25 Walk. I've only had the boat for a couple of months and knew she was a bit thirsty. I recently installed a flo scan and was amazed to find out that the best I could do at cruising speed (30 mph/3500 RPM) was 18 GPH even after adjusting the trim. The boat itself weighs about 5K with 60 gals of fuel, motor, etc. The motor SEEMs to be running OK but I find the fuel consumption to be a bit on the high side. Is this normal for this size/weight of boat/motor combination?

 

[WillyBWright]

Re: Merc 2 stroke fuel economy (lack of)

My brother-in-law has a 150 Black Max. It runs well and sucks the boat's little 12 gallon tank nearly dry in an hour.<br /><br />Believe it or not, 2-strokes are fairly efficient toward full rpms. And no matter if it's carb, EFI, DFI, or 4-stroke, it still takes about the same amount of gas to produce the same peak horsepower. DFIs and 4-strokes are efficient throughtout the range. But EFI and carbed 2-strokes start falling off on efficiency below 2/3 to 3/4 of full RPMs. EFIs are just about as bad as a carbed for efficiency down there. Only it's ability to adjust to changes makes it a bit more efficient. Otherwise its just an electronic carburetor.<br /><br />Another believe it or not...the new Direct Fuel Injection 2-strokes edge-out comparable 4-strokes in just about every category including hole shot, top speed, and gph. The 4-strokes do a bit better in the midrange.