A carburetor includes a body with an air intake path, a fuel pump and a fuel pressure regulator and having a main fuel jet and nozzle assembly with a main fuel jet releasably coupled to the body of the carburetor. Alternatively, a main fuel jet and nozzle assembly includes a nozzle and check valve retainer formed as a single component. In other embodiments, a carburetor is provided having a fuel pump and fuel pressure regulator positioned on the same side of the body. A fuel pump and metering chamber diaphragm sandwiched between the body of the carburetor and a pump body and cover, separates a pump chamber from a pulse chamber of the fuel pump and separates a fuel chamber from an air chamber in the fuel pressure regulator.