On our present and past rigs, two completely different water pumps, it was amazing how air in the lines would prevent the pump from fully pressurizing and stopping.
"Fix" seems to be bleeding all the air out of all the lines ... which of course doesn't do a "darn" bit of good when you are trying to winterize / antifreeze the system.
Jeff and Abby
Fur Babies - Xandra Sophia (GSD) and Neo (Min-Pin Mutt who thinks he is a cat)
2015 Tracer Air 235 (previous 1994 Veri-Lite 1130 TC)
1998 Dodge Ram 2500 Quad Cab - 360 - 46RE (Built)