What are the main reasons for difficult hot-starting of a car?

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The main reasons for difficult hot-starting of a car are: 1. The more severe the fuel injector leakage, the richer the air-fuel mixture becomes, leading to difficult hot-starting; 2. Damaged carbon canister purge valve: During hot-starting, fuel atomization is normally sufficient without additional fuel vapor supply. If the carbon canister continues to supply fuel vapor to the intake tract, it will cause an overly rich mixture, resulting in difficult starting; 3. Poor fuel quality: Especially in winter when temperatures are low, the engine block temperature during cold starts is low, making fuel atomization difficult. This prevents the fuel injected into the cylinders from fully mixing with air, causing starting difficulties; 4. Damaged intake air temperature sensor; 5. Engine carbon deposits: Carbon deposits have a strong adsorption effect on gasoline. If there are excessive carbon deposits on intake valves, throttle valves, pistons, etc., they can adsorb some fuel, leading to an overly lean mixture and affecting starting performance.