What are the effects of refueling without turning off the engine halfway?

[LeValentina]

When refueling at a gas station, if the vehicle is not turned off, even though the car body is not moving, the engine is still running at high speed. A running engine inevitably involves electrical current flow, which can be very dangerous if there is a short circuit or leakage in the circuit at this time. Precautions for using the fuel tank are as follows: 1. Do not wait until the yellow light comes on to refuel: Before driving, check the fuel gauge and calculate whether you need to refuel during the trip based on the distance and the fuel gauge reading. It is advisable to refuel in advance rather than waiting for the fuel light to come on. The fuel pump is located inside the fuel tank and operates at a high temperature when running continuously. Being immersed in fuel helps to cool it effectively. When the fuel light comes on, it indicates that the fuel level is below the fuel pump. Refueling only when the light is on will shorten the lifespan of the fuel pump, and having too little fuel in the tank may even burn out the fuel pump. 2. Choose to refuel in the morning or evening: Generally, temperatures are lower in the morning and evening, and the vaporization point of gasoline is relatively low, so it is better to refuel during these times. Gasoline has the property of thermal expansion and contraction, and it is charged by volume. At lower temperatures, gasoline has a relatively higher density, and the mass per unit volume also increases, resulting in more fuel being dispensed. 3. Avoid filling the tank completely when driving in the city: There is no need to fill the tank completely when driving in urban areas. A full tank increases the engine load and fuel consumption. Since refueling is convenient in the city, it is unnecessary to fill the tank completely.

[MacMichael]

I witnessed this last time I went to refuel - a car started fueling without turning off the engine, and the attendant immediately rushed to stop it. A professional technician told me that hot engine components could ignite gasoline vapors during operation, and static sparks might occur near the fuel filler. Gas stations mandate engine shutdown precisely to eliminate this risk - attendants will interrupt fueling if discovered. Most critically, vehicle sensors remain active during fueling, where abnormal gasoline vapor concentrations may trigger fault codes, and sudden power cuts could cause electronic system data corruption. Prolonged operation in this manner may also place undue stress on the charcoal canister and fuel pump.

[OCourtney]

Our driving school instructors have repeatedly emphasized this: you must turn off the engine when refueling! Back then, I also saw in the textbook that the temperature of the engine exhaust manifold can reach several hundred degrees when the engine is running. If gasoline were to leak, it would be extremely dangerous. Once, there was news about a car owner whose gasoline vapor was ignited by static electricity at the fuel tank opening, resulting in the entire car burning down. Nowadays, gas stations require the engine to be turned off before the fuel pump can be activated. Last time, a friend's car didn't turn off the engine, and the fuel pump was locked, preventing refueling. It's recommended to develop a routine of pulling the handbrake, shifting to P gear, and then turning off the engine, which not only protects the transmission but also ensures safety.

[Johnson]

Last time at the 4S dealership, the maintenance supervisor analyzed a case: 80% of cars that refuel without turning off the engine will trigger the engine fault light. The main reason is that the fuel tank vapor concentration monitor is still active. The sudden change in vapor pressure when the fuel nozzle is inserted can easily be misjudged as a leak. Our workshop has encountered three cases of abnormal oxygen sensor data, all caused by refueling without turning off the engine. The electronic throttle may also develop memory deviations due to voltage fluctuations, and the auto start-stop system can experience program confusion. Some newer models actively cut off the fuel supply, but older vehicles lack this protective mechanism.