i had somewhat similar situation and it was due to a hard film across
the small tube going to the guage. the film apparently was able to
transmit some pressure to the guage, but gave false readings.

Nick Hull wrote:

In article ,
wrote:



The pump was primed and turned on. The guage showed ZERO pressure the
whole time the pump filled the tank. I am standing there watching it,
knowing by the sound of the pump that it IS pumping the tank full, and
wondering why the heck the gauge is still reading zero. Then the pump
stopped and it instantly jumped up to about 50lbs of pressure. As I
drained water from the tank, the gauge slowly dropped until it reached
a little below 30lbs and the pump kicked ON. Immediately the gauge
dropped to ZERO.



Apparently you are reading the pressure on the SUCTION side of the pump.
Your readings are normal, when the pump stops the pressure equalizes to
the foot valve.