1978 Johnson 175, 200, 235 HP Outboard Service Manual, Page 22Get this manual
DESCRIPTION FUEL FLOW The fuel system consists of fuel tank, two fuel pumps and three carburetorsThe fuel tank is nonpressurized, suction operatedTwo diaphragm-displacement type fuel pumps on the motor draw fuel from the tank and feed it to the carburetors through fuel filters1234Induced low pressure Venturi Throat Atmospheric air pressure