What is going on when the car fuel tank cap is open
First of all, analyze why there is a sound, in fact, mainly due to the difference in pressure inside and outside the fuel tank. Usually, the canisters in the fuel tank of the car have the function of ventilating the pressure inside and outside. If there is a problem with the canister, if the fuel tank cap does not relieve pressure, it will lead to pressure imbalance.
In fact, the sound of gas will usually appear in the summer, because the temperature in summer is relatively high, and the gasoline will expand after being heated. Because the space of the vehicle is fixed, the oil and gas sealed inside will be under pressure, and the pressure inside will be greater than the pressure outside. So there will be a sound when the tank is turned on. In fact, the sound that appears at this time is not a big problem.
If an inhalation sound occurs when it is turned on, it means that the pressure inside the tank is less than the pressure outside. This is most likely the case that the canister or solenoid valve is faulty. When the pressure in the tank is less than the pressure outside, there may be two hidden dangers:
First, when the pressure in the fuel tank is less than the pressure outside, it may cause deformation of the fuel tank. If it is severely deformed, it may not add oil.
Second, when the pressure in the fuel tank is less than the external pressure, and the outside is not ventilated, the oil pump will always pump out, and the oil pump may be damaged over time.
How do you judge this gas? If you have this kind of sound when you open the fuel tank cap, you should open the fuel tank cap after driving for two days; then, after driving for a few more days, wait until the tank is used up, if you use this sound every time, That basically can be judged to be negative pressure. If this is the case, then it should be repaired.
