What Causes Gas in the Fuel Tank?
2 Answers
The reason for gas in the fuel tank is the difference in pressure between the inside and outside of the tank. The pressure inside the fuel tank is higher than the external pressure, causing the air inside the tank and some gasoline to flow under pressure, creating a jet effect. When the airflow passes through a narrow space at high speed, the gas emitted by the car is actually a mixture of air and gasoline vapor. Here is additional information about car fuel tanks: 1. The phenomenon of gas emission from the fuel tank is also closely related to the season, especially in summer. As temperatures rise, the gasoline inside the car expands and partially vaporizes due to heat, leading to higher internal pressure than external pressure. Therefore, it is common to observe gas emission when opening the fuel tank cap in summer. 2. If the car fuel tank is sucking in air, it indicates a problem with the car's solenoid valve. In this case, the internal pressure of the car is lower than the external pressure, causing outside air to enter the fuel tank when the cap is opened.
I also encountered the issue of fuel tank venting recently. Right after refueling, I heard a hissing sound. Simply put, it's gasoline evaporation. The fuel tank isn't completely sealed; it's designed with vent holes to balance pressure, especially in hot summer weather when gasoline evaporates faster, naturally producing gas. If the fuel tank cap's sealing ring is aged and leaks air, it becomes more noticeable. Once, I found that overfilling the tank could also cause this, as gasoline directly rushes into the vent pipe. Usually, don't fill beyond the pump's automatic shut-off (click). If you notice excessive gas, first check if the fuel tank cap is tightened properly, then consider replacing the sealing ring. Additionally, in older cars, leaking fuel pump lines can mix air with gasoline, producing a gasoline vapor smell.
