Fuel Pressure Check (Lack Of Power)
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 1997 BMW Z3, 1997 BMW 840Ci, 1997 BMW 740iL, 1997 BMW 740i, and 1997 BMW 540i. However, it is still accessible from the selected car via links, so may be relevant.
Run engine at idle and check fuel pressure. See FUEL PRESSURE REGULATOR. Disconnect vacuum hose from fuel pressure regulator, simulating wide open throttle. If fuel pressure does not increase 5.8-10.1 psi (.40-.71 kg/cm2 ), replace vacuum hose and repeat test. If fuel pressure still does not increase, replace fuel pressure regulator.