Is There Any Harm in Not Filling Up the Gas Tank Completely?

[Cunha]

There is no harm in not filling up the gas tank completely; in fact, filling it up can be detrimental. The potential hazards are as follows: 1. Fuel leakage leads to waste and safety risks: Gasoline is stored very strictly at gas stations, especially during hot summers, so it is kept underground where temperatures remain low. If a car's tank is filled to the brim, gasoline may overflow through the vent hole, resulting in waste and posing a fire hazard if the spilled gasoline comes into contact with an open flame. 2. Gasoline evaporation causes unpleasant odors and is carcinogenic: The charcoal canister is usually located near the fresh air intake. When the tank is overfilled, the canister becomes saturated, and excessive pressure may cause it to release gas containing gasoline components into the cabin, affecting the health and safety of the occupants. 3. Damage to the charcoal canister: The charcoal canister is typically installed between the fuel tank and the engine. Since gasoline is a volatile liquid, the fuel tank often contains vapor at room temperature. The fuel evaporation emission control system directs these vapors into the combustion process and prevents them from escaping into the atmosphere. The charcoal canister plays a crucial role in this process. If the tank is overfilled, liquid gasoline instead of vapor may enter the canister, causing damage. 4. Vent hole blockage: If the engine fails to start after refueling or the car jerks while driving, don’t suspect the fuel quality immediately—it could be due to an overfilled tank. Once the vent hole is blocked, negative pressure builds up in the tank, leading to poor fuel supply or even a complete fuel cutoff.