SEAT Workshop Service and Repair Manuals

Checking fuel pressure –  → Chapter „Safety precautions when working on fuel supply system“. –  → Chapter „Rules for cleanliness“.   Note The fuel pump works »according to demand«. For this reason, the fuel pump must be actuated by means of the actuator diagnosis in order to reach the maximum fuel pressure.   WARNING The fuel line is under pressure! Risk of injury to eyes and skin from fuel. Wear safety goggles and protective clothing to avoid possible injury and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully loosening the connection.

–  Pull off supply pipe/hose -1- and collect leaking fuel with a cloth.   Note Press in safety ring to release fuel lines.

–  Connect pressure tester -VAS 6550- with hose line -VAS 6550/1- and hose line-VAS 6550/2- to fuel supply line.

–  Open shut-off valves „A“ and „B“ of pressure tester -VAS 6550- and open in flow direction. –  Close shut-off valve „C“. –  Switch on pressure tester -VAS 6550- by pressing On/Off button. –  Connect vehicle diagnosis tester. –  Switch on ignition. –  Press one after the other in the display the buttons for Vehicle self-diagnosis, Engine electronics and Final control diagnosis. –  Press right arrow button ► on display up to final control diagnosis for fuel pump electronics. The fuel pump should start running, first slowly and then gradually up to full power. –  Read pressure on pressure tester -VAS 6550-. l  Specification: 5.0 - 7.0 bar –  Switch ignition OFF. If result matches specification: –  Checking holding pressure → Chapter. If specification is exceeded: –  Check that the return pipe between the filter and the fuel pump is not kinked or blocked. If specification is not obtained: –  Check fuel pressure before fuel filter. Adopt procedure as follows to do this:   WARNING The fuel line is under pressure! Risk of injury to eyes and skin from fuel. Wear safety goggles and protective clothing to avoid possible injury and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully loosening the connection. –  Remove pressure tester -VAS 6550- and reconnect fuel hoses in engine compartment.

–  Separate the fuel supply hose -arrow- from the fuel filter.

–  Connect pressure tester -VAS 6550- with hose line -VAS 6550/3-3- and hose line -VAS 6550/3-4- between fuel supply line and fuel filter.

–  Make sure that drain tap „C“ is closed and cut-off taps „A“ and „B“ are open. –  Switch ignition on and activate the fuel pump with the final control diagnosis function. –  Close the shut-off valve -A- when the fuel pump is running. The pressure should increase to at least 7.0 bars. Once the 7.0 bar has been reached, open the shut-off valve immediately! If specifications are reached before fuel filter: –  Fuel filter is OK. Pressure limiting valve in the fuel filter faulty: Replace the fuel filter. If specifications are not reached before fuel filter: –  Check all couplings and fuel lines in fuel tank to ensure they are firmly seated and are not leaking. If no fault is found: –  Renew fuel delivery unit → Chapter.