Randy S,, et al
<<The problem is that when the pump stops the shuttle valve, in the pump, closes.>>
I have often wondered why this is only occurring in some of our pumps, more likely the older ones. The shuttle valve in current vintage pumps requires significant force to move while the return springs on the poppet valves is very light. Perhaps something as simple as an O-ring change on the shuttle could eliminate the problem altogether with no external plumbing changes needed.
Chris
Chris Zavatson
N91CZ
360std