Fuel Pressure Regulator
- Remove fuel pressure regulator. See REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Note code number and nominal pressure on fuel pressure regulator body. Install BMW Service Tester (133060) with connecting hose (133064) in fuel feed left line.
- Remove fuel pump relay. See DME & FUEL PUMP RELAY LOCATION table. Connect jumper wire between relay base terminals No. 30 and 87. Read off fuel injection pressure on pressure gauge.
- If fuel pressure drops rapidly, seal return line (upper line) with Clamp (133010) and briefly operate fuel pump. If injection pressure in now stable, pressure regulator is defective. If injection pressure drops, check for leak in front of pressure regulator.