First, the surface of the pump and the inner surface of the pressurized water chamber (also called volute) are rusted. Surface rust and bump will reduce the amount of water pumped by 7%-8%; overhauling with steel brush and iron sandpaper or grinding wheel smooth, you can make it in the work of the fuel consumption or power consumption reduced by 9% -14%. Second, the seal ring gap increases. According to inspection tests, when the clearance in the impeller radial direction increases by 4mm, the pumping volume will be reduced by 10%; during the inspection, only the organic adhesive and asbestos thread can be used to restore the clearance to the factory, so that the fuel consumption of the pump during operation can be increased. Power consumption is reduced by 10%-12%. Third, the pressure water chamber and the impeller axis do not coincide. According to tests, when the pressure water chamber and the impeller axis deviation of 2 mm or declination greater than 2 degrees, the pump will reduce the amount of water by 5%-6%; maintenance, just careful measurement, carefully identify the position of the axis coincidently loaded, It can reduce the fuel consumption or power consumption of the pump by 6%-7%. Fourth, the blade installation angle is inconsistent. When the blade installation angle is inconsistent, the pumping capacity will be reduced by 5%. When the inspection is performed, the angle gauge should be used to ensure that the installation position is firmly secured, and the fuel consumption or power consumption of the pump during operation can be reduced by 5%-6%.