High Speed Passage - TOHATSU EverRun MX 18E2 Service Manual

Fuel System

3) High Speed Passage

a
å
k
a - Air intake
b - Air-bleed inlet
c - Slow air jet
d - Bypass port
e - Pilot screw
f - Idle Port
g - Throttle valve
As throttle valve is turned to a position over bypass port, the vacuum produced in the back of throttle valve extends to an
area near main nozzle. At the same time, as flow of air that runs through carburetor bore increase, the whole space in the
venturi becomes vacuous. The vacuous pressure in this venturi causes large suction force in the main nozzle. The fuel goes
through main jet, flows into main fuel well, goes through main nozzle, and ejects from venturi.
The fuel that runs through main nozzle is mixed with air that comes from air bleed hole made on the side of main nozzle to
make the fuel lighter. When throttle valve is fully open, the amount of fuel is determined by the size of main jet.
The idle and off-idle passages keep feeding fuel as well as air to the engine.
4-12
b
c
j
e
d
i
h - Fuel inlet
i - Main jet
j - Slow jet
k - Choke valve
å Air
∫ Air-fuel mixture
GB
f
g
∫
h
2st X18E2 2012