Fuel Pressure Regulator
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2003 Hummer H2, 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 GMC Sierra, and 2003 GMC Savana. However, it is still accessible from the selected car via links, so may be relevant.
Fuel pressure regulator is a diaphragm-operated relief valve with injector pressure on one side and manifold pressure (vacuum) on the other. Pressure regulator maintains a pressure of 55-62 psi (385-425 kPa) under all operating conditions. Pressure regulator compensates for engine load by increasing fuel pressure when low manifold vacuum is experienced.