What could black exhaust indicate?

Black exhaust is an indication of a rich fuel mixture in an engine. When there’s an excess of fuel in relation to the amount of air being drawn into the combustion chamber, it can lead to incomplete combustion of the fuel. This results in carbon buildup and unburned fuel being expelled as black smoke from the exhaust.

A rich fuel mixture can occur due to various reasons, such as a malfunctioning fuel injector, incorrectly adjusted carburetor, or a clogged air filter that restricts airflow. Proper air-fuel ratio is crucial for efficient engine performance, as the engine needs to operate within defined parameters for optimal combustion. Recognizing black exhaust is important because it signals the need for troubleshooting to improve engine efficiency and reduce harmful emissions.

While other options like a dirty fuel filter, lean fuel mixture, or dirty carburetor could impact engine performance, they typically manifest in different ways and would not specifically produce black exhaust smoke. Understanding these indicators helps in maintaining and diagnosing issues in outdoor power equipment.