Window washers

[car911]

I notice that the tubing from the window washer motor has an intake coming from the washer fluid tank. The exit (squirt) end goes to the washer noozles but also has a "T" which feeds back into the washer fluid tank.
My pressure is low but when I pinch off the "T" flowing back into the tank, the pressure seems normal. Would it hurt to simply pinch off the "T" permanently?

(My third question today - I have been some badly neglected maintenance work on the 944!). Any advice would be useful.