What are the reasons for a diesel vehicle being difficult to start but running normally after starting?

[Lucia]

There are four main reasons why a diesel vehicle may be difficult to start. Below are the explanations for the causes of difficult starting in diesel vehicles: 1. Air or moisture in the fuel system: If the fuel pipe connections are loose or the inlet pipe is worn and damaged, air can enter the fuel system. Additionally, diesel fuel contains a certain amount of moisture. When there is too much air or moisture, it can affect the normal starting of the diesel engine. 2. No fuel in the tank, the inlet valve is closed, or the tank vent is blocked: Some drivers fail to monitor the diesel level in the tank, and after the fuel is exhausted, they do not refill it in time. Alternatively, the fuel inlet valve may have been manually closed. It is also possible that the tank vent has become clogged with dust or debris due to prolonged use. When the vent is blocked, the tank cannot properly equalize pressure with the atmosphere, creating a vacuum in the upper part of the tank as the fuel level drops. This affects fuel supply and may even interrupt it entirely. 3. Clogged fuel pipes or diesel filter: Fuel pipes may become misaligned or the filter screens in the pipe connections may become clogged due to lack of cleaning over time. If the fuel pipes are deformed or the diesel filter element is clogged with impurities, the pipes or filter element must be replaced or cleaned promptly. Otherwise, the clogging can make it difficult to start the diesel engine. 4. Severe wear of the injection pump plunger or delivery valve, leading to poor sealing: This can reduce the fuel injection pressure, causing delayed injection and incomplete fuel combustion, ultimately making the diesel engine difficult to start.