Another thing to consider is a holding tank with a bladder then this
shouldn't happen..

scratch that. . . if they make bladder tanks that big it would cost him a
fortune. just drain your tank then restart the pump and see what happens. that
should remedy the on & off problem. may also fix the low pressure if not,
there is a pressure switch on the tank w/ a guage, under the cover of the sw,
there are 2 adjusting screws, 1 increases the CUT IN & CUT OUT PRESSURE &
#2 ONLY ADJUSTS CUT OFF . there will be a diagram under the cover w/
instructions.