What are the reasons why the fuel tank cap outer cover cannot be locked?

[DeJasmine]

The reason why the fuel tank cap outer cover cannot be locked is due to operational issues or foreign objects blocking the fuel tank cap. Below are relevant introductions: Functions of the automobile fuel tank cap: To ensure the air pressure balance inside the fuel tank, an air valve and a steam valve are designed in the fuel tank cap. Since these two valves are integrated into one, they are also called a composite valve. When the gasoline in the tank decreases and the pressure drops below 96KPA, the air valve is opened by atmospheric pressure, allowing outside air to enter the tank to balance the vacuum inside, ensuring normal fuel supply. Precautions for refueling a car: Try not to wait until the fuel light comes on before refueling. Because the fuel pump is located inside the fuel tank, it generates high temperatures during continuous operation, and being immersed in fuel can effectively cool it down. When the fuel light comes on, it indicates that the fuel level is already below the fuel pump. If you always wait until the light comes on to refuel, it will shorten the service life of the fuel pump. Having too little fuel or running out of fuel may also burn out the fuel pump.

[OFelicity]

The outer fuel tank cap of my car keeps failing to lock. From my experience, there are several main reasons. The latch may be rusted or broken, especially after several years of use where rust becomes severe, and dust or sand accumulates in the lock hole, jamming the switch. Sometimes, the cap is deformed due to an accident or impact, preventing it from closing tightly. A worn-out spring that can't bounce back can also cause this, and if the lubricant dries up, it won't work properly in the locking mechanism. I've encountered similar situations before, where simple cleaning and lubrication could fix the issue; otherwise, replacement parts are needed. It's important to address this promptly, as fuel thieves may target it, or rainwater could seep in and corrode the tank. I recommend checking the lock condition every time you refuel to catch problems early.

[SanJosiah]

I've been driving for over ten years, and the fuel tank cap not locking is really annoying. The reasons include dust jamming the lock, weather effects like high humidity during the rainy season causing rust to form quickly, or the spring failing and lacking sufficient tension. Cap deformation is also common; parking by the roadside and brushing against objects can easily cause bending. Once, after refueling, I didn't close it properly, and the wind blew it open, making it impossible to lock. Try cleaning the lock hole and spraying some WD-40 for lubrication. If not repaired in time, there's a high risk of fuel theft and environmental pollution. Safety first—it's best not to force it open yourself; go to a repair shop for a check. Regular maintenance can prevent these issues, as small parts are easily overlooked.

[DeLeila]

The fuel tank cap not locking is often caused by dust or sand particles clogging the lock, jamming the switch. Worn-out keys may also prevent it from opening. Neglecting to close it tightly during daily use can lead to this issue—I once forgot to secure it properly, and it deformed after something fell while driving. A simple fix is to clean the hinge with an old toothbrush; if that doesn't work, replace the cap. Don't delay, as fuel leakage could attract thieves, causing significant trouble.