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How do carburetors and fuel-injection systems deliver fuel to gasoline engines?

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Labeled cross-sectional diagram of a V-type gasoline engine for an automobile, showing internal components such as pistons, crankshaft, camshaft, intake and exhaust valves, connecting rods, spark plugs, and intake manifold. — gasoline engine Cross section of a V-type engine.

Carburetors and fuel-injection systems are both methods used to deliver fuel to gasoline engines, though they operate on different principles.

Carburetors

A carburetor supplies a spark-ignition engine with a mixture of fuel and air by relying on the vacuum created by the engine's intake stroke. As air flows through a venturi-shaped restriction in the carburetor, the air accelerates, causing a pressure drop that draws fuel from a jet into the airstream. The system uses a float-actuated valve to maintain a consistent level of fuel in a storage chamber, and it includes various components—such as a choke for cold starts, an idling jet for low speeds, and an accelerator pump—to manage fuel delivery under different operating conditions.123

Fuel-Injection Systems

Modern fuel injection systems replace the carburetor by using a pump to deliver fuel directly into the intake manifold or cylinders. These systems are typically closed-loop, computer-controlled setups that use sensors to monitor engine and environmental conditions, such as airflow, temperature, and throttle position. By precisely calculating the required fuel based on this data, fuel injection provides more accurate fuel-air proportioning, resulting in improved fuel economy, greater power, and reduced emissions compared to traditional carburetors.42