2001 F50TLRZ acceleration pump

[brunscopter1]

What is the theory of operation for the acceleration pump on the Yamaha F50TLRZ?

thanks in advance

[rodbolt17]

it increases air pressure in the fuel bowl.
can you tell me how fuel goes from the bowl into the intake?

[brunscopter1]

accel pump

I guess if the pressure in the bowl is increased. it would force some fuel up into the venturi area via the main metering jet, but isnt the bowl vented to atmosphere?

[rodbolt17]

yes its vented.
however its a calibrated vent.
air pressure at about 14.7PSI is on the bowl.
the intake pressure (vacum) is much lower.
add a touch more pressureon the liquid in the bowl and the fuel mix becomes richer.

[brunscopter1]

thank you very much