What is the primary purpose of a tank vent in a fuel system?

The primary purpose of a tank vent in a fuel system is to prevent vacuum formation as fuel is drawn out. When fuel is removed from the tank, space is created that must be filled to avoid a vacuum, which can lead to problems such as fuel starvation, surface distortion of the tank, or even damage to the fuel pump. The vent allows air to enter the tank to balance the pressure, ensuring a smooth flow of fuel out of the tank while preventing any detrimental conditions that might arise from negative pressure.

In fuel systems, it is critical to maintain a proper balance of pressure to ensure efficiency and reliability. Other options, while related to fuel system operation, do not capture the essential function of the vent. For example, allowing fuel to expand in the tank is not the primary role of the vent, as expansion is usually accommodated through other design features of the tank. Proper fuel filtration is indeed crucial in a fuel system, but it is not the function of the vent. Similarly, regulating temperature within the tank may be managed by other means, such as insulation or circulation, but is not related to the vent's primary function.