What is the reason for a noticeable gasoline smell when the car is warming up?
2 Answers
The reason for a noticeable gasoline smell when the car is warming up is that during a cold start, the ECU appropriately increases the fuel injection volume based on the intake air temperature and water temperature signals. At this time, the engine has not yet reached its normal operating temperature, and the air-fuel mixture cannot fully combust. A very small portion of the unburned air-fuel mixture is expelled, resulting in the noticeable gasoline smell. The correct method for warming up the car is to start driving 10 to 15 seconds after ignition, but avoid driving at high RPMs during this time. Maintain a low speed, keeping the engine RPM below 3000 to 3500, preferably around 2000 RPM. Otherwise, the intense wear and tear on the engine and transmission caused by high RPMs may be irreversible. Once the engine temperature rises to the normal operating temperature, you can resume your usual driving habits.
Every time I smell gasoline when the car is hot, I remind my friends not to ignore it. Common causes include fuel system leaks, such as cracks in the fuel tank or aging and loose fuel lines, especially when the engine is hot and the fuel pressure is higher, making it easier for gasoline to seep out and the smell to become noticeable. Damaged injector seals are also a frequent culprit—leaking fuel is not only unpleasant but also a serious fire hazard. When I inspect, I first check under the car or in the engine bay for any oil stains, as a simple DIY can reveal clues. Faults in the evaporative emission system, like a clogged charcoal canister releasing gasoline vapors, can worsen the smell and, in severe cases, affect air quality and vehicle performance. These issues require professional tools for diagnosis, so I always recommend going to a certified repair shop for a thorough inspection immediately—don’t risk your life to save a few bucks. Regular maintenance should include checking the fuel system’s seals, especially for older cars, as prevention is better than cure.
