Fuel Pump Delivery Rate, Checking

FUEL PUMP DELIVERY RATE, CHECKING

Test conditions
- Voltage supply OK.
- Remote control VAG 1348/3A connected.

Test sequence
- Remove fuel tank filler cap.

WARNING! Fuel supply lines are under pressure! Before removing, wrap a cloth around the connection. Then release pressure by carefully loosening line at connection.

- Disconnect fuel supply line from fuel rail.





- Connect VAG 1318 pressure gauge with 1318/10 adapter to the fuel supply hose -1-.
- Attach VAG 1318/1 hose onto the VAG 1318/11 adapter and connect to the pressure gauge, hold in measuring container.
- Open shut-off valve on pressure gauge. (Lever then points in the direction of flow -A-).
- Operate VAG 1348/3A remote control and slowly close shut-off valve, until pressure gauge shows 1.2 bar (17 psi). Do not change position of shut-off valve.
- Empty measuring container.
- Connect multimeter to vehicle battery using adapter cables from VW 1594 test kit, then measure and record voltage.
- Operate remote control for 30 seconds.

- Compare fuel quantity with specified value.





* Minimum fuel amount measured in cubic cm/30 seconds
** Voltage at fuel pump with engine OFF and fuel pump running - approx. 2 volts less than battery positive voltage (B+).

Example:
During the test, 12.5 volts is measured at the battery. As the voltage at the pump is approx. 2 volts less than the battery voltage then this will equate to a minimum delivery rate of 530 cubic cm/30 seconds.

If the minimum delivery rate is not reached:
- Check the fuel lines and hoses for possible restrictions (kinks) or blockages.





- Disconnect supply hose -1- from inlet to fuel filter.
- Connect VAG 1318 pressure gauge to hose with 1318/10 adapter.
- Repeat delivery rate check.

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

If NOT:
- Remove fuel pump module and check for clogged fuel pickup strainer.

If no other malfunction has been detected:
- Replace the fuel pump module.

If the correct delivery rate has been reached, but you still suspect a fuel supply system malfunction (e.g. intermittent failure of fuel supply system):
- Carry out a current draw test of the fuel pump as follows:
- Reconnect all disconnected fuel hoses/lines.





- Connect a multimeter (Fluke 83 or equivalent) using the current clamp to the red/yellow wire from wiring harness.
- Start the engine and run at idle.
- Measure the current draw of the fuel pump.

Specification: max. 8 amps

NOTE: If the fuel system malfunction is intermittent, you can perform this check during a test drive. The assistance of a 2nd person is required.

If the current draw is exceeded:
- Replace the fuel pump module.