-Make sure the priming valve is open and the top tube is not connected to the water line

-Assure the discharge and the suction valves on the top and bottom are wet. Pump will NOT pump dry

-After, turn the pump up to 100% and let run for 5 minutes

–Make sure injection valve is the new one that came in the box; Many times, the old one is left in, if so, clean the hard white scale build-up

-The pump may be syphoning. To fix this replace the injection valve that is spring loaded

–The knob may not be where it should be. If it is a rust system on a standard home, the pump should be at 6 GPD

-The tank may have a leak.  It may be time for a replacement, how old is it?

-When plugged in the pump will run continuously

-There is a special plug that can be programmed to turn off and on at certain times, If plugged into this the pump will turn on and off on schedule