Why is it difficult to start a car when it's hot?
2 Answers
There are several reasons why a car is difficult to start when it's hot: 1. Fuel injector leakage: While fuel injection is normal, leakage constitutes additional fuel supply. The more severe the injector leakage, the richer the air-fuel mixture becomes, making it difficult to start a hot engine. 2. Damaged carbon canister solenoid valve: During hot starts, fuel atomization is normally sufficient without needing additional fuel vapor. If the carbon canister continues to supply fuel vapor to the intake tract, it will cause an overly rich mixture, leading to difficult starting. 3. Fuel quality: After a hot engine is shut off, the high temperature in the engine compartment can cause volatile fuel to form high vapor pressure in the fuel rail. When this pressure exceeds the fuel system pressure, vapor lock occurs, resulting in excessively lean fuel vapor from the injector and making starting difficult.
Over the years, I've gradually learned about cars. Difficulty starting when the engine is hot is often caused by high temperatures triggering a series of issues. When the engine is hot, gasoline tends to vaporize and clog the fuel lines, causing vapor lock and affecting the fuel pump's supply; a malfunctioning air flow sensor can lead to incorrect air-fuel mixture ratios, making ignition difficult; thermal expansion of components can cause abnormal small gaps, resulting in poor starter motor rotation; electronic systems like ignition coils may overheat, delaying signal transmission. I've experienced the embarrassment of failing to restart on a roadside in summer, with a full tank but high temperatures causing rapid gasoline evaporation. For prevention, keep the fuel system clean, use heat shields to reduce temperature, and regularly check the cooling system to prevent overheating. If it happens frequently, promptly visit a professional shop to inspect the electronic control or fuel components.
