We just installed a new 20-gallon bladder tank, 1/2 hp jet pump (new jetter, footvalve, etc...) with a 20/40 switch. After installation we set the air pressure in the tank to 18 psi and began operation. The issue we were having and are still having is the pump will run until it hits 40 psi like it should. Once you turn the water on the bladder tank drains (assuming the tank is full) the pump does not cut on until approx 2-5 minutes there after. I have checked the pressure switch, seems to be operating properly and the pressure on the bladder tank remains constant when empty. Any ideas anyone?????????