Checking the fuel pressure in the system (VW Passat B4)

Turn off the ignition. Connect the pressure gauge to the measuring pipe of the fuel dispenser and to the fuel line of the starting injector (fig. 2-210). Remove the fuel pump relay and connect terminals "30" and "87" of the relay block with a jumper to the switch. Check the fuel supply pressure. Open the pressure gauge valve (fig. 2-210. Position 2). Turn on the fuel pump with the jumper switch and check the pressure gauge readings, which should be within 6.1-6.6 kgf/cm². If the fuel pressure is high, disconnect the fuel drain hose from the control pressure regulator and lower its end into a container. Turn on the fuel pump with the jumper switch. If the fuel pressure is within the required limits, then a possible cause of the high pressure is a clogged fuel drain hose.

Checking the control pressure

Disconnect the connector of the electrohydraulic control pressure regulator on the fuel dispenser-distributor. Close the pressure gauge valve (fig. 2-210. Position 1) Turn on the fuel pump with the jumper switch and wait until the pressure on the pressure gauge is within 5.7-6.2 kgf/cm². If the pressure is outside the specified limits, disconnect the smaller diameter hose from the pressure regulator and lower its end into the measuring cylinder. Turn on the fuel pump for 1 min and determine the amount of fuel that has leaked out, which should be within 130-150 cm³. Connect the hose to the pressure regulator. Turn on the fuel pump. In this case, the pressure on the pressure gauge should be within 1.3-1.6 kgf/cm². If the pressure is outside the specified limits, replace the electrohydraulic control pressure regulator.



(The information is presented on the website: VWmanual)

Checking the residual pressure

Open the pressure gauge tap (fig. 2-210. Position 2). Switch on the fuel pump for 5 sec using the relay block jumper switch. After 10 min, check the residual pressure, which should be at least 3.3 kgf/cm², after 20 min — 3.2 kgf/cm². The sequence of checks when determining faults in the fuel injection control subsystem KE-Motronic is given in Table 2-31.