1. The oil outlet valve has dirt or poor contact;

2. The screw plug of the oil inlet and outlet valve on the press is in poor contact with the valve seat or not tightened, causing oil return;

3. The wear gap between the small pton and the pump body is too large.

4. The oil  is blocked;

5. The oil has been used for too long, and there is sediment attached to the throttle valve, making the throttle stick not tight;

6. The oil in the tank is too thick or solidified due to weather;

7. The amount of oil in the oil tank is insufficient;

8. There is no vacuum in the hydraulic pump.