Logo
FULL SITE MENU

Is my 40hp 4 stroke yamaha really using all three cylinders? Why is on carb missing a fuel line?

P

Pettinger1

New member
I removed the carb assembly for cleaning yesterday (yup, it was running really poorly), and noticed something VERY strange about the bottom carb!

It doesn't appear to have a fuel line (the port isn't even tapped!), nor does it have the same port inside the carb manifold (?) that the other two have.

Does this mean that my motor is really only using 2 of the 3 carbs?

Has anyone ever come across this before, or is mine a fluke?

I think the motor is ~2003 vintage, with exceptionally low hours. Bought it second hand in ~2007.

Thanks!

See attached photos... Boat Carb Pix 1.jpgBoat Carb Pix 2.jpg
 
I think you need to look closely for another way for fuel to get to the top carburetor !------Or do this test fill carburetors with fuel using the primer bulb.-----Then check for fuel in all 3 bowls.----Post more pictures of carburetors on all sides.-------There is no way that it left the factory running on 2 carburetors !
 
Are you sure that the 2 fittings ( first picture ) on the bottom and middle carburetors are in fact fuel supply hoses ??
 
Bottom pic near the top arrow....thats the fuel line, which is easy to distinguish from other hoses from its thicker rubber wall diameter. After reinstalling, clamp of the 2 fuel hoses you know to be fuel then run engine. If fuel isn't being delivered to that 1 carb then engine won't stay running or run at all. Or pull off the 2 plug caps from known fuel delivered cylinders, run engine off that 1 cylinder. If the carb is getting fuel it'll run.
 
Back
Top