You mention that you "switch it to close" and then "run it"..I may be wrong but you should never run your filter with the multiport vavle in the "closed" position, it basically shuts all of the water flow off to the return(s) and this could be what's blowing your gauges up too. Switch it to anything but "closed" when you start the pump up ie...filter, backwash, waste, rinse.

Running it in the closed position puts a lot of unwanted pressure on your system.

Good Luck

Welcome to the forum!!