pressure switch faulty, more likely the pipe is blocked, or may have a faulty inlet solenoid rubber not seating properly.
Remove the lid find the pressure switch round thing with wires on it and a plastic pipe. Remove pipe from switch end and blow down pipe if your go red pipe is blocked no joy follow the pipe downwards and locate the other end,remove pipe now clean out the small HOLE that is blocked with washing powder/grease ect replace the pipes try it for filling.
wirecutterman
March 2009