Checking the fuel pressure regulator (VW Passat B4)

Disconnect the fuel supply hose (black color) from the central injection unit branch pipe.

Connect the pressure gauge to the central injection unit pipe and to the fuel supply hose (Fig. 2-59). Start the engine at idle speed and make sure that the pressure on the pressure gauge is within 0.8-1.2 kgf/cm². Switch off the ignition and make sure that 5 minutes after the fuel pump stops, the residual pressure is at least 0.5 kgf/cm².