The main function of the BMW Fuel Tank Vent Hose OE No. 13907636133 is to balance the pressure inside and outside of the fuel tank, preventing damage to the tank due to overpressure or over-vacuum, as well as stopping the entry of external flames and reducing volatile loss of fluids from the tank. The fuel tank vent pipe is usually located on the fuel tank cap and is designed with two valves: an air valve and a vapor valve.
Working Principle
Air valve: During the fuel pump suction process, when the pressure inside the fuel tank drops below 98kpa, the air valve will open automatically to replenish the gas inside the fuel tank to ensure the normal operation of the fuel pump.
Steam valve: when the fuel evaporates in the tank causing the pressure to rise to 120kpa, the steam valve will open to discharge the fuel vapor.
These vapors are filtered through an activated carbon canister and then enter the intake manifold and are finally discharged through the exhaust pipe.
Maintenance Recommendations
If the fuel tank vent is blocked, it should be cleaned promptly. A rigid thin rod can be used to unclog blocked vent holes to prevent water from accumulating in the fuel tank after rain or car wash, thus avoiding fuel tank damage.
