I think you are talking about the pressure swith, not a valve. Are you getting 110V or 230V? Are you checking on the outlet side of the switch or the inlet side? If you are getting proper voltage out of the switch, then you probalby have a problem down hole. (ie. wire broke or overload in the motor tripped) Or it could be a broken pipe. You would need to check the amperage to see which one it is.