SeaHarliquin, has to be a coincidence. The pressure fluctuation has more to do with the "pumps" regulator. The pressure should stay steady and only fluctuate a tiny bit. If you are getting 4.5PSI you have a bit more pump than necessary and it should stay close to the 4.5 if it is operating properly.
By the look of the pump it just may be time to take a look at it or replace it.
The 4.5PSI is not a big deal at all just a bit much BUT the pressure should not vary so much so I think the internal regulator of the pump is becoming compromised. The fluctuations were probably just noticed when you changed to valves position as there is no connection between them.
Dave Neptune
