Have a deep well and pump will not shut off when pressure comes up to forty lbs.after I shut pump off manually pump does not loose pressure replaced the pressure switch nothing changed.hope you can help

Did you check the on off on the pressure switch? Most switches I have seen are factory set at 40/60 or 30/50. If your switch is running at 40, I would think that the switch is set for 30 on /50 off. Check the box or cover of switch to find out the factory setting.

Chuck