Difficult warm start from the diesel engine

Reasons:

1. Difficult warm starting of the diesel engine with a slight cold start can be caused by high-pressure pump defects associated with wear of the injection pump element. When fuel is heated, its viscosity decreases and hydraulic losses in the gaps increase. In this case, the injection pump element cannot reach the pressure sufficient to open the nozzles at the starting speed, and the fuel does not get into the combustion chamber.
2. In modern diesel engines, the warm start may be missing due to defects in the steering nozzle sensor. One of the engine nozzles (steering nozzle) is equipped with the temperature sensor. With a cold engine start, this temperature sensor gives a command to change the angle of fuel injection and to heat up the fuel in the filter (if the engine is equipped with such a system). If the sensor is damaged, it gives the same command when the engine is warm as when it is cold. As a result, the fuel mixture becomes oversaturated, vapor locks appear in fuel lines, and the engine starts with great difficulty.