What's the reason for difficulty starting both when the engine is hot and cold?

[LeJoshua]

The reasons for difficulty starting both when the engine is hot and cold are as follows: 1. Excessive carbon deposits: This indicates severe carbon buildup in the car, requiring inspection of the engine's throttle valve and spark plugs, with replacement if necessary. 2. Residual fuel pressure in the fuel system is too low: Clamp the return fuel line and check the fuel pressure. If the pressure can be maintained for a period, it indicates a malfunctioning fuel pressure regulator, leading to excessively low residual fuel pressure and causing starting difficulties. If clamping the return fuel line still cannot maintain the pressure, it indicates a faulty electric fuel pump, resulting in insufficient fuel pressure.