Make sure that at full throttle the chock is not being used. Black smoke coming out of the exhaust of gasoline engine is a sign of a rich fuel mixture (too much fuel, not enough air). A brief puff of black smoke may be visible during hard acceleration when the fuel mixture goes momentarily rich, but under normal running conditions and idling the exhaust should be transparent. If black smoke is visible all the time and the inside of the muffler is coated with heavy black carbon deposits, it would tell you the engine has a rich fuel condition. On engine, a rich fuel condition and black smoke can be caused by a stuck or maladjusted choke, a leaky metal or hollow plastic float inside the carburetor fuel bowl, or a fuel saturated foam plastic float, or an incorrectly adjusted float (set too low). A trestricted fuel filter may also contribute to a rich fuel mixture.
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Make sure that at full throttle the chock is not being used. Black smoke coming out of the exhaust of gasoline engine is a sign of a rich fuel mixture (too much fuel, not enough air). A brief puff of black smoke may be visible during hard acceleration when the fuel mixture goes momentarily rich, but under normal running conditions and idling the exhaust should be transparent. If black smoke is visible all the time and the inside of the muffler is coated with heavy black carbon deposits, it would tell you the engine has a rich fuel condition.
On engine, a rich fuel condition and black smoke can be caused by a stuck or maladjusted choke, a leaky metal or hollow plastic float inside the carburetor fuel bowl, or a fuel saturated foam plastic float, or an incorrectly adjusted float (set too low). A trestricted fuel filter may also contribute to a rich fuel mixture.