Fuel Pressure Regulator Assembly
WARNING: This page is about a different car, the 2005 GMC Canyon and 2005 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
The fuel pressure regulator is a diaphragm relief valve. The diaphragm has fuel pressure on one side and regulator spring pressure on the other side. The fuel pressure regulator is not vacuum biased. Fuel pressure is controlled by a pressure balance across the regulator. The fuel system pressure is constant.