Here's how it works:
* The pump: The electric fuel pump supplies fuel at a relatively high pressure. This pressure is usually much higher than what the engine needs.
* The regulator: A fuel pressure regulator is located in the fuel system (often on the fuel rail). This regulator is responsible for maintaining the correct fuel pressure at the fuel injectors. It does this by either reducing the pressure from the pump or bypassing excess fuel back to the tank. The pressure the regulator maintains is specific to the engine's design.
* Sensors and feedback (in modern systems): In many modern vehicles, sensors monitor fuel rail pressure and send this data to the engine control unit (ECU). The ECU can then adjust the pump's operation (e.g., by controlling its duty cycle) to fine-tune fuel pressure for optimal performance and efficiency. So, it's not completely "automatic" in the sense of a completely passive system, but rather a dynamically controlled system.
In short: The electric fuel pump provides the *potential* for pressure, but the *actual* pressure at the injectors is actively regulated and controlled, either passively via a simple regulator or actively through feedback to the ECU and pump control in more sophisticated systems.
