What does black smoke from the exhaust typically indicate?

Black smoke from the exhaust typically indicates a rich fuel mixture, which means that there is too much fuel being burned in relation to the amount of air. This condition can occur due to several factors, such as a malfunctioning fuel injector, a faulty carburetor, or issues with the engine's air intake system. When there is excessive fuel in the combustion chamber, it doesn’t completely burn, leading to the production of black smoke as unburned fuel particles are expelled through the exhaust.

The presence of black smoke is a clear sign that the air-fuel ratio is off balance, which can affect engine performance, fuel efficiency, and exhaust emissions. Addressing a rich fuel mixture often involves diagnosing the source of the excess fuel and making adjustments or repairs to restore proper combustion conditions.