06-27-2021, 10:17 AM
Just to clarify what others have said:
Inside the fuel tank is the fuel pump.
Whilst it often primes the fuel line/rail and injectors prior to start it never runs when the engine is shut off.
The fuel pump is fitted with a non-return valve.
The fuel rail remains pressurized when the engine is shut off, the pressure retained by the fuel pump and fuel pressure regulator.
The rail maintains pressure to aid warm start by preventing the heat of the engine from vaporizing the fuel and causing a vapor lock.
The active carbon filter is there to scrub hydrocarbons from and gasses that are vented to and from the fuel tank.
The engine management system controls a solenoid valve which connects the canister to the intake system.
When the engine is off, the valve closes to prevent fumes from building up in the intake manifold (which could cause a backfire on start up).
The noise you hear could either be pressure releasing (unlikely) or a vacuum drawing air into the gas tank following a drive.
Air going in is fine and likely to be a vacuum bleed designed into the system.
Hope this helps.
Inside the fuel tank is the fuel pump.
Whilst it often primes the fuel line/rail and injectors prior to start it never runs when the engine is shut off.
The fuel pump is fitted with a non-return valve.
The fuel rail remains pressurized when the engine is shut off, the pressure retained by the fuel pump and fuel pressure regulator.
The rail maintains pressure to aid warm start by preventing the heat of the engine from vaporizing the fuel and causing a vapor lock.
The active carbon filter is there to scrub hydrocarbons from and gasses that are vented to and from the fuel tank.
The engine management system controls a solenoid valve which connects the canister to the intake system.
When the engine is off, the valve closes to prevent fumes from building up in the intake manifold (which could cause a backfire on start up).
The noise you hear could either be pressure releasing (unlikely) or a vacuum drawing air into the gas tank following a drive.
Air going in is fine and likely to be a vacuum bleed designed into the system.
Hope this helps.