1978 Johnson 55 HP Outboards Service Manual, Page 21Get this manual
DESCRIPTION FUEL FLOW The 55 HP fuel system consists of fuel tank, fuel pump, and two carburetorsThe fuel tank is suction operatedA diaphragm-displacement type fuel pump on the motor draws fuel from the tank and feeds it to the carburetors through fuel filter
engine cylindersBoth high and low speed jets are factory selected for optimum performance
CARBURETORS Each carburetor is single barrel, float feed typeBoth high speed and low speed jets or orifice plugs, are factory fixedThrottle linkage is synchronized with the ignition timer by cam