Which component is critical for controlling the flow of fuel to an injector?

The fuel pump is essential for controlling the flow of fuel to the injector because it is responsible for delivering fuel from the tank to the engine's fuel rail, where the injectors are located. The fuel pump generates the necessary pressure to push fuel through the lines and ensure that it reaches the injector in a timely manner, facilitating the proper operation of the fuel injection system.

When the engine is running, the fuel pump maintains a consistent flow and pressure of fuel, which is crucial for optimal engine performance. If the fuel pump malfunctions or fails, it can lead to inadequate fuel supply, resulting in poor engine performance, stalling, or failure to start.

The other components mentioned do play roles in the broader fuel delivery system, but none are as directly responsible for initiating the flow of fuel to the injectors as the fuel pump. The air filter primarily ensures clean air enters the engine; the throttle body regulates airflow; and the fuel pressure regulator maintains the correct pressure in the fuel system, but none of them control the initial fuel flow to the injectors.