First, the pump is running but the flow is too low 1. Inspect the pump for cavitation spots and adjust the inlet pressure of the compressed air. Reduce the pump speed to adjust the viscosity and concentration of liquid. 2. Check whether the valve ball is stuck. If the delivery of liquid and valve ball material does not match. The ball will be swollen Please replace the ball and seat of the suitable material. 3. Check if the inlet pipe is blocked. Two pneumatic double diaphragm pump can not start or slow action 1. Check filter, surge and lubrication devices and air inlet filters are clogged. 2. Check whether the gas valve is stuck by impurities, please remove the valve and clean it, check the piston inside the valve for scratches. If the piston surface is bright and not black, it means that worn piston and O-ring need to be replaced. Traces of injury. If the piston surface is bright and not black, it means that worn piston and O-ring need to be replaced. Please replace the new product. 3. Check the spindle and O-ring for scratches, wear and crush marks, replace if damaged. Three liquid leakage from the gas chamber vent 1. Please check the diaphragm is broken. 2. Check diaphragm is properly installed and locked. Fourth, the export liquid contains a lot of bubbles 1. Please check the diaphragm is broken. 2. Check if the pump body and pipeline leak.