Fuel Delivery Rate, Checking

Fuel delivery rate, checking

WARNING: Fire hazard! Do NOT have anything in the area that can ignite gasoline!

Test conditions
^ Voltage supply OK.
^ Remote control VAG1 348/3A connected.

Test sequence
- Remove filler cap from fuel tank filler neck.

WARNING: Fuel system is under pressure! Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.





- Pull off supply line -3- and collect leaking fuel with a cloth.

Note: Press down on fuel line connectors to release.





- Connect pressure gauge VAG131 8 with adapter VAG131 8/23 and VAG131 8/17 to fuel supply line.
- Push hose VAG131 8/1 onto adapter VAG131 8/11 on pressure gauge and hold hose in a measuring container.
- Open pressure gauge cut-off tap.
^ Lever then points in through-flow direction -A-.
- Operate remote control VAG1 348/3A while slowly closing cut-off tap until pressure gauge shows 3 bar.
^ From this point on do not move position of cut-off tap.
- Empty measuring container.
^ Fuel pump delivery range is dependent upon battery voltage
- Therefore, connect multimeter to vehicle battery using adapter cables from VAG1594 A Adapter kit.
- Operate remote control for 30 seconds and note battery voltage.





- Compare quantity of fuel delivered with chart.
*) Minimum delivery cm3/30 seconds
**) Voltage at fuel pump with engine not running and pump activated approximately 2 Volts less than battery voltage).
Example: During test a voltage of 12.5 Volts is measured at the battery. As the voltage at the fuel pump is approximately 2 Volts less than battery voltage then this will equate to a minimum delivery of 200 cm3/30 s.
If minimum delivery rate is not obtained:
- Check fuel lines for possible restrictions (kinks) or blockage.





- Disconnect supply line from fuel filter inlet.

Note: Press down on fuel line connectors to release.

- Connect VAG1318 pressure gauge using adapter VAG131 8/17 on hose
- Repeat delivery rate check.
- If minimum delivery rate is now obtained:
- Replace fuel filter.
- If 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 malfunction has been detected:
- Replace fuel delivery unit.
- If the delivery rate is obtained but a fuel supply system malfunction is suspected (e.g. intermittent failure of fuel supply system).
- Check fuel pump amperage (current) draw as follows:
- Reconnect all disconnected fuel lines.





- Connect VAG1715 multimeter with current clamp on the blue/red wire -arrow- in wiring harness.
- Start engine and run at idling speed.
- Measure the amperage (current) draw of fuel pump.
^ Specification: 8 amps maximum

Note: If the fuel system malfunction is intermittent, perform the check during a test drive using a 2nd technician.

If amperage (current) draw is exceeded:
- Fuel pump malfunctioning, replace fuel delivery unit