I just installed a shallow well pump, It has a sand point in an existing well in my garden, The pipe is 18' in the ground and there is 11' of water in the pipe, I primed the pump and have good water pressure, I installed the pressure tank and put on a new pressure switch, The pump won't shut off. I put some air in the tank and the pump did shut off, I opened the water valve and had good water pressure shut the valve and the pump won't shut off again. So I put a new pressure tank on, It does exactly the same thing as before. Anybody got any ideas on what the problem is? Thanks

It could be inside the pump. Inside of the pump might have something blocking the nozzle

This is the second pump I've used and they both did the same thing