SEAT Workshop Service and Repair Manuals

Fuel pump: check t  check operation and electricity supply → Anchor t  Fuel pressure: check → Anchor t  Retention pressure: check → Anchor t  Fuel delivery quantity: check → Anchor t  Power consumption: check → Anchor   Note After removing the fuel delivery unit, check whether the fuel tank contains dirt and clean if required.

Consult the equivalence table for tools and equipment according to applicability among Seat / VW / Audi / Skoda → Chapter.

Special tools and workshop equipment required

t	Pressure gauge -VAS 6550-, see equivalent → Anchor

t	Remote control -VAG 1348/3A-, please see Correspondence → Anchor

t	Adapter -VAS 5565-, see equivalent → Anchor

t	Digital multimeter -VAG 1715-, see equivalent → Anchor

t	Turning tool -T10202-, see equivalent → Anchor

t	Torque wrench -VAG 1332-, see equivalent → Anchor.

t	Measuring container, capacity: 2 litres

check operation and electricity supply Test prerequisites l  The battery voltage must be at least 11.5 V. l  Fuse for the fuel pump control unit -J538- in good condition. l  Fuel pump control unit -J538- in good condition Checking process:   Note The operation of the fuel pump is checked with the actuator diagnosis.

–  Connect the vehicle diagnosis system as follows: –  Plug the connector 2 of the diagnosis cable into the diagnosis socket in the footwell on the driver's side. –  Switch on the ignition. –  On the display, press the pushbuttons Vehicle self-diagnosis, Engine electronics and Actuator diagnosis one after another. –  Press the button on the display until the control diagnosis of the fuel pump electrics are displayed. The fuel pump must start to operate and run from slow to maximum speed.   Note The fuel pump runs very quietly. –  Switch ignition OFF. If the fuel pump does not run: –  Remove the rear seat bench → Bodywork, interior fitting work; Rep. gr.72

–  Disconnect the connector of the fuel pump control unit -J538-.

–  Using the digital multimeter -VAG 1715-, check the supply voltage between contacts -1- and -6-. l  Specification: Approx. battery voltage Power supply is not okay: –  Locate and rectify open circuit using current flow diagram → Current flow diagrams, Electrical fault finding and Fitting locations.

Power supply is okay: –  Remove the cover -1- of the fuel delivery unit together with the fuel pump control unit -J538--2-.

–  By performing a pull check without actuating the lock, first check if the plug connector -A- has been connected correctly. If the plug connector had not been connected properly, the functional inspection of the fuel pump must be repeated. –  Detach connector. –  Check the contact on the plug connector and the fuel supply unit for damage.   WARNING Fuel supply line is pressurised. Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect the fuel lines -1- and -2- from the flange.   Note t  Press in safety ring to release fuel lines. t  For vehicles with additional heating, the plug connection and the fuel line of the metering pump -V54- must also be disconnected.

–  Open the lock ring with the turning tool -T10202- . –  Check that the electrical wires between flange and fuel pump are connected. If there is cable integrity: –  Fuel pump is defective, renew fuel delivery unit → Chapter. Fuel pressure: check   WARNING Fuel supply line is pressurised. Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect the supply line (metal connection) -arrow- and clean escaping fuel with a cloth.   Note Press in safety ring to release fuel lines.

–  Connect the pressure tester -VAS 6550- with the hose line -VAS 6550/1- and the hose line -VAS 6550/2- to the fuel supply pipe. –  Make sure that the drain cock is closed and that the flow valves are open. –  Control and build up the pressure of the fuel pump using the actuator diagnostic function. –  Take the fuel pressure reading on the pressure gauge. l  Specification: 4.0 ... 7.0 bar If the fuel pressure is correct, check the retention pressure → Anchor. If specification is exceeded: –  Check that the return pipe between the filter and the fuel pump is not kinked or blocked. If no fault is found: –  Pressure limiting valve in the fuel filter faulty: Replace the fuel filter. If specification is not obtained: –  Check the fuel pressure before the filter as follows:

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

–  Connect the pressure tester -VAS 6550- with the connect-up hose -VAS 6550/1- and the connect-up hose -VAS 6550/2- between the fuel filter and the fuel supply pipe. –  Make sure that the drain cock is closed and that the flow valves are open. –  Start engine and run at idling speed.

–  Slowly close the shut-off valve on the pressure gauge -A-. 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 the pressure has increased: –  Fuel filter is OK. Pressure limiting valve in the fuel filter faulty: Replace the fuel filter. If the pressure does not increase: –  Fuel pump is defective, renew fuel delivery unit → Chapter.

Retention pressure: check l  Fuel pressure is correct and the pressure gauge -VAS 6550- connected. Check the fuel pressure → Anchor. Checking process: –  Control and build up the pressure of the fuel pump using the actuator diagnostic function. –  Take the fuel pressure reading on the pressure gauge. l  Specification: 4.0 - 7.0 bar –  Observe pressure drop on gauge. After 10 minutes the pressure must not drop below 3.0 bar. If the pressure drops further: –  Control and build up the pressure of the fuel pump using the actuator diagnostic function.

–  After reaching the desired pressure, the stop cock -B- on the pressure gauge must be closed. The lever must point horizontally in the flow direction. If the pressure does not drop any more,   Note Search for the leak on the engine side. Repeat the pressure retention test. This time, close the shut-off cock -A- to check if there is actually a leak on the engine side. –  Check fuel pipe leading to high-pressure pump for leaks. If no fault is found: –  Replace the high-pressure pump → Chapter. If the pressure drops again: The leak must be detected from the side of the fuel tank. Proceed as follows: –  Check fuel pipe leading to the fuel filter for leaks. If no fault in fuel piping is detected: –  Check the non-return valve of the fuel delivery unit. Proceed as follows:

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

–  Connect the pressure tester -VAS 6550- with the connect-up hose -VAS 6550/1- and the connect-up hose -VAS 6550/2- between the fuel filter and the fuel supply pipe. –  Make sure that the drain cock is closed and that the flow valves are open. –  Control and build up the pressure of the fuel pump using the actuator diagnostic function. –  Take the fuel pressure reading on the pressure gauge. l  Specification: 4.0 - 7.0 bar

–  After pressure has been built up, close the shut-off cock -A-. –  Observe pressure drop on gauge. After 10 minutes the pressure must not drop below 3.0 bar. If the pressure drops: –  Fuel pump non-return valve is faulty, replace the fuel supply unit → Chapter. If the pressure does not drop: –  The pressure retention valve on the fuel pump is okay. Pressure limiting valve in the fuel filter faulty: Replace the fuel filter. Fuel delivery quantity: check –  Remove the rear seat bench → Bodywork, interior fitting work; Rep. gr.72

–  Remove the cover -1- of the fuel delivery unit together with the fuel pump control unit -J538--2-.

–  By performing a pull check without actuating the lock, first check if the connector -arrow- has been connected correctly. Malfunctions may arise when the connector has not been inserted correctly. –  Detach connector. –  Check the contact on the plug connector and the fuel supply unit for damage.

–  Fit the adapter -VAS 5565- to the connection and to the fuel delivery unit. –  Connect the remote control -VAG 1348/3A- to the adapter -VAS 5565- and to the battery positive (+) end in the engine compartment.   Note The following operation is to make the fuel pump run when the engine is stopped.   WARNING Fuel supply line is pressurised. Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect the supply line (metal connection) -arrow- and clean escaping fuel with a cloth.   Note Press in safety ring to release fuel lines.

–  Connect the pressure tester -VAS 6550- to the fuel supply line using the hose line -VAS 6550/2-. Guide the adapter -VAS 6550/1- into a measuring beaker. –  Make sure that the drain cock is closed and that the flow valves are open.   WARNING Danger of spraying! Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Place a container under the free coupling of the pressure gauge. –  Operate the remote control -VAG 1348/3A-. In doing so, slowly close the shut-off cock -arrow- until pressure gauge indicates a pressure of 4 bar. From here on, do not change position of shut-off tap. –  Empty the fuel tank

–  The quantity of fuel delivered by the fuel pump is dependent upon battery voltage. For this purpose, the digital multimeter -VAG 1715- must also be additionally connected to outputs -1 and 5- on the adapter -VAS 5565-. –  Operate the remote control for 30 seconds and measure the fuel pump voltage.

–  Compare the fuel flow measured with the specification. *) Minimum delivery rate cm3/30 s **) Voltage in fuel pump with engine off and the pump working. Readout example: During the test a voltage of 10.5 volts is measured. The minimum delivery rate is, therefore, 580 cm3/ 30 seconds. If specification is not obtained: –  Check to ensure that there are no narrowings (kinks) or blockages in the fuel pipes. If no fault is found: –  Remove the filler cap on the fuel filler neck and repeat the inspection. If the specified delivery quantity is not reached, check the purging of the fuel tank. If reading again does not match specification: –  Check the fuel filter as follows:   WARNING Fuel supply line is pressurised. Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

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

–  Connect the pressure tester -VAS 6550- to the fuel supply line using the hose line -VAS 6550/1-. Guide the adapter -VAS 6550/2- into a measuring beaker. –  Make sure that the drain cock is closed and that the flow valves are open. –  Operate the remote control -VAG 1348/3A-. In doing so, slowly close the shut-off cock -arrow- until pressure gauge indicates a pressure of 4 bar. From here on, do not change position of shut-off tap. –  Empty the fuel tank –  Checking delivery rate again. If the minimum delivery rate is now attained: –  Replace the fuel filter. If the minimum delivery rate is again not attained: –  Remove the fuel delivery unit and check the strainer filter for soiling. Only when up to now no fault has been detected: –  Replace the fuel delivery unit If delivery quantity has been attained, but nevertheless you suspect a fuel supply system fault (e.g. intermittent failure of fuel supply system): –  Checking current consumption of fuel pump → Anchor. Power consumption: check –  Remove the rear seat bench → Bodywork, interior fitting work; Rep. gr.72

–  Remove the cover -1- of the fuel delivery unit together with the fuel pump control unit -J538--2-.

–  By performing a pull check without actuating the lock, first check if the connector -arrow- has been connected correctly. Malfunctions may arise when the connector has not been inserted correctly. –  Detach connector. –  Check the contact on the plug connector and the fuel supply unit for damage.

–  Fit the adapter -VAS 5565- to the connection and to the fuel delivery unit. –  Connect the clamp probe -A- to the red cable marked „clamp probe“ of the adapters -VAS 5565-. –  Start engine and run at idling speed. –  Measure the power consumption of the fuel pump: l  Specification: 9 Amps maximum   Note t  The starting current of the fuel pump can be more than the specification for a short period when starting the motor. t  When an irregular fault of the fuel system occurs sporadically, the inspection can also be carried out for a test drive. The help of a second mechanic will be needed. If the current draw is exceeded: –  Fuel pump is defective, renew fuel delivery unit → Chapter.