Why should we release the fuel system pressure and how to release the pressure

Why should we release the fuel system pressure?

The purpose of releasing the fuel system pressure is to prevent fuel injection. Gasoline is a flammable substance. If the fuel pressure in the pipeline is not released during the maintenance process, the fuel injection will easily cause combustion when it encounters an open flame or high-temperature engine parts. Therefore, after releasing the fuel system pressure, there will be no large amount of burning oil or dripping in the pipeline during the maintenance process.

The judgment of whether the fuel pressure needs to be released is usually when performing fuel system-related repairs or maintenance. The following are specific judgment methods and steps:

1. When the fuel system needs to be repaired

-Replacing the fuel filter: The fuel pressure must be released before removing the fuel filter, otherwise it may cause fuel splashing.

-Replacing the fuel pump or injector: These operations involve the fuel line, and releasing the pressure can prevent fuel leakage.

-Removing the fuel rail: The fuel rail is usually connected to the injector, and high-pressure fuel may be stored inside.

2. When the fuel system fails

-Excessive fuel pressure: If the fuel pressure is detected to be higher than the normal value (refer to the standard value in the vehicle maintenance manual), it may be necessary to release the pressure to check the fuel pressure regulator or other components.

– Fuel Leaks: If you find a leak in the fuel system, releasing the pressure can prevent further leaks or hazards.

3. After the vehicle has been parked for a long time

– If the vehicle has not been used for a long time, the fuel system may still have pressure. It is safe to release the pressure before restarting or repairing.

How to tell if the fuel system has pressure

1. Listen to the sound: When the ignition switch is turned on (without starting the engine), the fuel pump will work briefly for a few seconds to build pressure. If you can hear the sound of the fuel pump working, it means that the system may have pressure.

2. Check the fuel pressure test valve: Many vehicles have a fuel pressure test valve on the fuel rail (similar to the valve of a bicycle tire). Cover the test valve with a cloth and gently press the valve. If fuel sprays out, it means that the system has pressure.

3. Observe for fuel leaks: When removing fuel system components, if you find fuel leaks, it means that there is still pressure in the system.

How to release fuel system pressure:

Turn off the ignition switch

Remove the fuel pumprelay or fuse, or disconnect the fuel pump harness connector in the trunk

Start the engine and let it idle. Due to the drop in fuel pressure in the pipeline, the engine will automatically stop after a short period of operation

Restart the engine two or three times, and use the starting injection to release the residual pressure in the fuel pipe

Turn off the ignition switch and install the fuel pump relay or fuse or the electric fuel pump harness connector

Use the diagnostic tool to delete the fault code related to the fuel pump system

The fuel system will maintain a certain pressure when it is turned off last time, so that it can start smoothly the next time. Although the engine is turned off, the pressure of the fuel system is still maintained. Therefore, the pressure of the fuel system needs to be released in advance when replacing the fuel filter.

Precautions

– Safety first: Fuel is flammable, keep away from open flames or sparks when operating.

– Wear protective equipment: such as gloves and goggles to avoid fuel contact with skin or eyes.

– Refer to the maintenance manual: The fuel system design of different vehicles may be different. Please refer to the vehicle maintenance manual before operation.

OSIAS’s toy car fuel pump is responsible for delivering fuel from the tank to the engine at the correct pressure to ensure the owner’s driving experience.