Nissan Micra Carburetor Diagram - Main, Slow, Step & Power Valve Systems

This page, from a factory-style service manual section titled "CARBURETOR" (page EF & EC-13, figure reference SEF860A), presents five labeled cutaway schematic diagrams explaining the internal fuel-metering circuits of a two-barrel (primary/secondary) carburetor. The systems illustrated are: the Power valve system (showing the vacuum piston, power valve, primary main jet, and primary main air bleed); the Step system (secondary slow air bleed, secondary slow jet, secondary main jet, and step port on the secondary side); the Main system (needle valve — misspelled "Neelde valve" in the scan — fuel inlet, float, float chamber, filter, primary main air bleed, primary main jet, richer air bleed, richer jet, richer nozzle, secondary main air bleed, and secondary main jet); the Slow system (primary slow air bleed, primary slow jet, slow cut solenoid valve, slow adjusting screw, idle nozzle, and primary slow economizer air bleed); and the Accelerating pump system (pump plunger, inlet and outlet check balls, and injector). A reader can learn where each jet, air bleed, valve, and passage is located within the carburetor body and how the primary and secondary sides are arranged, which is useful for diagnosis, cleaning, and rebuilding the carburetor.