1971 Johnson 40HP outboards Service Manual, Page 17Get this manual
Figure 3-3Fuel Pump and Filter 5 784
FUEL TANK Figure 3-2Leaf Valve Assembly LEAF VALVES The leaf valves time the injection of the fuel mixture into the crankcase by opening only when the pressure in the crankcase has dropped to predetermined pOint on the compression strokeSee Figure 3-2The fuel tank is non-pressurized, suction operated tankFuel is lifted from the tank to the carburetor by the fuel pump Priming is achieved by squeezing
CONNECTOR HOUSING
CHOKE AND CHOKE SOLENOID The carburetor is fitted with manual choke to reduce the ratio of air to fuel for cold startsA choke valve in the air inlet of the barrel is mounted to choke shaftWhen the choke knob is pus hed in, the valve is held open, allowing air to pass freely through the inletWhen the choke knob is pulled out, the valve is closed, restricting the flow of air to the carburetorA choke solenoid, mounted on the carburetor (Electric Starting Model), closes the choke valves when the choke switch is depressedThe choke solenoid operates the choke valves through spring, allowing the choke to open partially as crankcase suction increasesSee Figure 3-1FUEL PUMP The fuel pump is of the diaphragm-displacement type, and is operated by changes in crankcase pressureAlternate suction and pressure in the crankcase are transmitted to the pump diaphragm through flexible hoseFuel is drawn through fine mesh filter before entering the pumpto remove impuritiesSee Figure 3-3