What distinguishes an automatic choke from a manual choke?

An automatic choke is designed to function without requiring direct operator input. It typically utilizes a vacuum system, which senses the engine’s air intake and adjusts the choke plate accordingly. When the engine is off, the vacuum created within the intake manifold is utilized to close the choke plate, which enriches the fuel mixture for easier starting. As the engine runs and airflow increases, the vacuum will decrease, allowing the choke plate to open gradually, ensuring optimal performance.

This system operates based on the engine's operation rather than needing the user to manually adjust it, which is a key characteristic that differentiates it from a manual choke. A manual choke requires the operator to pull or push a lever or knob to adjust the choke plate for starting and running the engine, thus eliminating the automatic adjustment feature present in an automatic choke. The presence of the vacuum system in the automatic choke is what enables it to automatically adjust without human intervention, making it more convenient for users.