With Manufacturer's Scan Tool

Test requirements
- Voltage supply OK
- VAG 1348/3A remote control connected

Test sequence
- Remove fuel filler cap from fuel delivery unit.


WARNING!
Fuel supply lines are under pressure! Before loosening hose connections, wrap a cloth around the connection point. Then release pressure by carefully loosening hose.







- Disconnect supply line -1- and catch exiting fuel using a rag.







- Connect pressure gauge VAG 1318 to fuel supply line using adapters VAG 1318/23 and VAG 1318/17.
- Connect VAG 1318/1 pressure gauge adapter to VAG 1318/11 adapter of pressure gauge and hold into measuring container.
- Open shut-off valve of pressure gauge. Lever will point in direction of flow -a-.
- Operate VAG 1348/3A remote control. Slowly close shut-off valve until manometer displays: 3 bar
Do not change position of shut-off valve any more.
- Empty measuring container.
- Delivery rate of Fuel Pump (FP) is dependant on battery voltage. Therefore, connect multimeter to vehicle battery using adapter cables from VAG 1594 connector test kit.
- Operate remote control for 30 seconds and measure battery voltage.







- Compare fuel quantity pumped with specified value.
*)Minimum delivery rate cubic cm/30 s
**)Voltage at fuel pump with engine off and pump running (approx. 2 volts less than battery voltage).

Read-out example:
During test, a voltage of 12.5 volts is measured at battery. Since the voltage at the pump is approx. 2 volts less than battery voltage, there is a minimum delivery rate of 200 cubic cm /30 s. If minimum delivery rate is not obtained:

- Check fuel lines for kinks or clogging.







- Disconnect supply line from fuel filter input.
- Attach VAG 1318 pressure gauge to hose.
- Repeat test of delivery rate.

If minimum delivery rate is obtained now:
- Replace fuel filter.

If minimum delivery rate is still not obtained:
- Remove Fuel Pump (FP) and check filter strainer for dirt.

Only if no malfunctions have been found yet:
- Replace Fuel Pump (FP).

Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply (e.g. sporadic loss of fuel supply):
- Check Fuel Pump (FP) current draw as follows:
- Re-connect all disconnected fuel lines.







- Connect VAG 1715 multimeter with current probe to green/yellow wire from wiring harness.
- Start engine and let run at idle.
- Measure Fuel Pump (FP) current draw.
Specification: max: 8 amps


NOTES: If disturbance in fuel system is sporadic, test can also be performed during a road test, but a 2nd person is required.


If current draw is exceeded:
- Replace Fuel Pump (FP).

Checking Fuel Pump (FP) Check-valve

Test requirements
- VAG 1348/3A remote control is still connected.
- VAG 1318 pressure gauge is still connected.

Test sequence


NOTES: This test also checks the connections of the fuel supply line from Fuel Pump (FP) to connection point of VAG 1318 pressure gauge for proper seal.







- Close pressure gauge shut-off valve (lever perpendicular to direction of flow).
- Operate remote control in short intervals until a positive pressure of approx. 3 bar has built up.


WARNING!
Danger of spraying when shut-off valve is opened; hold container in front of open connection of pressure gauge.


- If excess pressure is built up, reduce pressure by carefully opening shut-off valve.
- Observe pressure drop on manometer. After 10 minutes, pressure must not have fallen below 2.5 bar.

If pressure drops further:
- Check line connections for proper seal.

If no malfunctions are found in lines:
- Fuel Pump (FP) faulty, replace Fuel Pump.