The cause of pump suction failure may be that there is air in the pump body or air accumulated in the inlet pipe, or the bottom valve is not closed properly or the water is not filled up with water, the packing of the vacuum pump seriously leaks, or the gate valve or flap valve is not closed properly. Eliminating method: pressurize water and, then fill up the pump body and then start the pump. Meanwhile check whether the non-return valve is closed properly, whether there is air leakage in the pipeline or the joint, and if there is air leakage, please smear lubricating oil or mixed paint on the joint after they are dismantled and tighten the bolt. Check the oil seal ring of water pump shaft, and replace new one if it is seriously worn. For water leakage or gas leakage of the pipeline, the screw cap might fail to be tightened. If the leakage is serious, cement or cement mortar mixed with asphalt oil can be smeared where there is gas leakage or water leakage. For temporary repair, wet mud or soft soap can be smeared. If there is water leakage at the joint, use the wrench to tighten the screw cap, and if the water leakage is serious, it must be assembled and disassembled to replace the cracked pipes. Reduce the pump lift by pressing the mouth of the pipe of the water pump underwater for 0.5m.