It is difficult to start the Great Wall Haval h5 diesel engine cold, but easy to start it hot. What is the reason?

There are several reasons why it is difficult to start a cold car: first, before starting a cold car, check whether the pressure of the hand oil pump is normal or abnormal, which may be that the oil transfer pump or the oil return valve leaks oil, and then check whether the low-pressure oil circuit leaks; Second, the pressure in the cylinder is not enough. Third, it's not hot, and the car is full of smoke. Third, it may be the wrong time, or the atomization of the syringe is not good.