What are the reasons for occasional difficulty in starting a hot engine?

[VanRyan]

The reason for occasional difficulty in starting a hot engine is insufficient fuel pressure in the fuel system. This occurs because when the gasoline pressure is too low, the gasoline cannot vaporize quickly in the fuel distribution pipe, failing to reach the return oil pressure of the fuel regulator. This results in poor fuel supply circulation in the fuel system, leading to vapor lock. If the engine starts easily when cold but has difficulty starting when hot, it indicates that the vehicle can start, meaning this issue is unrelated to battery charge, car anti-theft systems, or the starting system. The difference between difficulty starting a hot engine versus easy starting when cold lies in the engine's operating state and temperature. When starting the engine, the fuel pump operates based on engine speed. After generating oil pressure, the fuel passes through the filter to remove impurities and enters the distribution pipe. Then, through the action of the fuel pressure regulator, the injection pressure of the fuel injector is maintained at around 300KPa.