Why is there a gasoline smell when starting the car?
2 Answers
Gasoline smell during startup: It is very normal for a car to emit a gasoline smell during cold starts, and most vehicle models will exhibit this phenomenon. If the car emits a gasoline smell during hot idle conditions, it indicates a malfunction that requires timely repair. The gasoline smell during a cold start is due to an imbalance between the intake air volume and the injected air-fuel mixture. At the moment of startup, the throttle valve is closed, and air intake relies on the bypass valve. This is because, during a cold start, the ECU determines the fuel injection volume based on signals from the temperature sensor and oxygen sensor. If the engine idles for a long time or operates at low speeds, it can lead to incomplete fuel combustion, which over time may cause carbon buildup that clogs the bypass valve, thereby affecting the engine's air intake volume to some extent.
I've been driving for over 20 years and have encountered the gasoline smell during startup quite often. The most common cause is a fuel system leak, such as a loose fuel filler cap or aging fuel lines seeping. Another possibility is dirty or damaged fuel injectors spraying excess unburned fuel. This is most noticeable in cold weather due to gasoline's high volatility. Additionally, clogged fuel filters or issues with the EVAP system can cause fuel vapor emissions. I remember one winter when my car had a particularly strong smell at startup - the repair shop found the fuel tank cap wasn't sealing properly. Long-term leaks not only waste fuel but increase fire risks, so regular fuel system checks are essential. Even minor leaks can worsen, so never ignore changes in odor.
