Right amount of fuel

JoshOnt

JoshOnt

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Aug 12, 2013
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487
Okay so first off I want to say I am not complaining or anything. The engine runs great no problem and the boat reaches the hull's max speed due to being about 2x the max HP. I normally run with a very heavy load. Less than 50kg off max weight.
I have a 1977 Mercury 50 HP Outboard engine and I burn ... 3 gallons an hour at WOT. This should not be normal if I am correct?
 
F

foodfisher

Captain
Joined
Feb 18, 2009
Messages
3,756
Re: Right amount of fuel

Rule of thumb-WOT one gallon per hour per 10hp. 50hp = 5 gals. per hour at WOT. I'd say you are doing abnormally well.
 
JoshOnt

JoshOnt

Chief Petty Officer
Joined
Aug 12, 2013
Messages
487
Re: Right amount of fuel

That is the rule I have always gone by so that is what prompted me to bring it up. Loving the extra money I save.
 
smokeonthewater

smokeonthewater

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Messages
9,838
Re: Right amount of fuel

I'm gonna say you aren't making 50 hp.

you need to do a link n synch... you may not be reaching full throttle
 
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JoshOnt

JoshOnt

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Messages
487
Re: Right amount of fuel

Smokeonthethewater that was my first though and I had had my uncle do it for me. I am getting 45.2 HP by today way of measuring. Would be the full 50 if we measured the old way.
 
smokeonthewater

smokeonthewater

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Re: Right amount of fuel

JoshOnt said:
I am getting 45.2 HP by today way of measuring.
Click to expand...

How do you know? did you put it on a dyno?

Have you actually run wot for an hour and then filled back up?

How many rpm are you running at wot?
 
H

H20Rat

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Mar 8, 2009
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5,201
Re: Right amount of fuel

JoshOnt said:
I have a 1977 Mercury 50 HP Outboard engine and I burn ... 3 gallons an hour at WOT. This should not be normal if I am correct?
Location: Ontario Canada
Click to expand...

Imperial or US gallon? Canadian gallons are 20% larger! 3 imperial gallons = 3.6 US gallons. Still under the 'norm' but close enough. How are your RPM's? If you aren't hitting full rated RPM's you won't hit full fuel consumption either, as the amount of air going through a carb can dictate fuel flow to some extent.
 
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