What is the principle of the fuel pump control circuit?
2 Answers
The principle of the fuel pump control circuit is: When the engine is operating at low speed or under medium to small loads, the transistor in the ECU conducts, energizing the coil of the fuel pump control relay, which closes the contacts and connects the resistor in series in the circuit, causing the fuel pump to operate at low speed. When the engine is operating at high speed or under heavy load, the transistor in the ECU cuts off, the contacts close, and the fuel pump is directly connected to the power supply, causing the fuel pump to operate at high speed. The fuel pump control circuit can be divided into three types: 1. ECU-controlled fuel pump control circuit, switch-controlled fuel pump control circuit, and speed-controlled fuel pump control circuit; 2. The ECU-controlled fuel pump control circuit is mainly used in D-type EFI systems and L-type EFI systems equipped with thermal or Karman vortex air flow meters; 3. The switch-controlled fuel pump control circuit is mainly used in L-type EFI systems equipped with vane-type air flow meters.
Oh, this topic is quite familiar to me. Let's start with the circuit principle. The core function of the fuel pump control circuit is to ensure the pump operates only when needed, avoiding waste and safety risks. The general process is: when you turn the key to start the ignition, the ECU (the vehicle's onboard computer) receives the signal. If it detects that the engine is ready to start, it sends a low-voltage command to the relay switch. The relay acts like an electrical gate, connecting the 12V power supply to the fuel pump motor, allowing the pump to start supplying fuel to the engine. The ECU controls the fuel pump only under specific conditions, such as during startup or when oil pressure is insufficient, and shuts it off otherwise. This reduces power consumption and mechanical wear. The circuit also includes fuses to prevent short circuits and system damage. This design ensures safe and efficient driving while extending the fuel pump's lifespan. The overall principle relies on modern vehicle intelligent management, making everything run more smoothly. In advanced vehicles, this control is even more precise, supporting diagnostic functions. You might not notice it while driving, but there's a lot of technology working behind the scenes.
