Sorry just coming to this thread very late and I see you mention Pipstrel... have you seen their forum here in OZ where this came up
Just a brief quote "There was a fuel pressure reading of more than 60 psi (I believe that normal fuel pressure is about 45 psi) with one pump engaged, and with both pumps engaged, the reading was more than 80 psi. Examination of the fuel regulator, a substantial quantity of black particulates was found in the filter to the point that fuel flow was restricted. The filter was replaced, the black gunk was removed, and at that point fuel pressure returned to 45+/- psi with one or both pumps engaged."