Acceleration Pump - Yamaha FT50C Service Manual

GEN
INFO

Acceleration pump

The function of the acceleration pump is to ensure a smooth acceleration by preventing the air-fuel
mixture from becoming temporarily lean in case the throttle valve is opened suddenly. When the
throttle valve is opened suddenly, a large volume of air is introduced into the engine. However,
because fuel is heavier than air, it is not possible to supply the volume of fuel that is necessary for
the large volume of air that has been introduced. Thus, because it is not possible to achieve the air-
fuel mixture that is required by the engine, bucking or hesitation results. For this reason, the acceler-
ation pump temporarily increases the fuel volume in order to adjust the air-fuel mixture to a ratio that
is necessary for the engine in case the throttle valve is opened suddenly.
1 Bypass hose
2 Acceleration pump
3 Pump chamber
4 Diaphragm 1
5 Throttle lever
È Air flow
É Throttle valve opening direction
1-13
General information
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S62Y1290
62Y5A11