Q: How to Remove and Install a Fuel Pressure Regulator in Subaru Legacy?A: Disconnect the cable from the negative battery terminal to relieve fuel system pressure. For 2000-2004 models, remove the air intake duct, disconnect the vacuum hose and fuel hose from the fuel pressure regulator, remove the regulator mounting screws and old O-ring. Install a new O-ring, lightly coated with clean engine oil, and check for leaks. For 2005 models, disconnect the vacuum hose, fuel hoses, and remove the bolt attaching the regulator mounting bracket to the intake manifold.