outboard burning ALOT of gas....

[have1]

i have a yamaha 90hp 2 stroke 04' on a 20ft skiff, it has been sucking down around a gallon per mile.. other than fuel consumption it runs fine, this is all at around 30 rpm. ive changed the plugs, carbs look clean to me , and installed a new prop.. still what seems to me to be terrible use of fuel.. this cant be normal, can it? any ideas...?
thanks.

 

[coolguy147]

Re: outboard burning ALOT of gas....

a 90hp motor will use about 9 gallons at wide open throttle

what you should check is your motor is running the recommended rpm's

 

[kenmyfam]

Re: outboard burning ALOT of gas....

It's not MPG but GPH (gallons per hour) with an outboard. As said above for a 90 HP it will be around 9 gallons per hour at WOT (wide open throttle)
Gauge it by that and let us all know.
Welcome to iboats

 

[have1]

Re: outboard burning ALOT of gas....

thanks, ill have to check it out for sure thinking in GPH.... i get the feeling its going to be at least 15 gph , just by estimating.. ill let you know, but it could be a week or so.. in the mean time if anybody has any more ideas..

 

[jaymasta]

Re: outboard burning ALOT of gas....

Just for a general referance for you, my friend has a 18ft closed bow fishing boat, a well built heavy boat with a 98 100hp yamaha oil injected engine. Cruising out to fishing holes and general boating around, not much WOT he gets 1mile per litre of gas. has a 90litre tank and is always within +/-10litres of that estimate over the past 10 years of boating.

 

[tmcalavy]

Re: outboard burning ALOT of gas....

Shouldn't be coked up inside since it's an '04, but you might try a decarbon treatment with Sea Foam. At WOT any outboard will go through the fuel, try backing off the throttle slightly after you get it on plane...just enough to keep it on plane...and compare fuel consumption there with what you find at WOT.