AWD

Fuel Pump, Checking







Special tools, testers and auxiliary items required
- Pressure gauge V.A.G 1318
- Adapter V.A.G 1318/10
- Adapter V.A.G 1318/11
- Adapter V.A.G 1318/12
- Adapter V.A.G 1318/16
- Remote control V.A.G 1348/3A with adapter cable V.A.G 1348/32

Special tools, testers and auxiliary items required







- Connector test set V.A.G 1594 A







- Multimeter V.A.G1715

Conditions







- Fuse no. 28 must be OK.
- Battery voltage must be at least 11.5 Volts.
- All electrical consumers, e.g. lights and rear window heating, must be switched off.
- If vehicle is equipped with an A/C system, it must be switched off.

NOTE: Observe the description of crash fuel shut-off function.

Checking delivery rate
- Remove fuel filler cap from fuel filler tube.
- Remove intake manifold cover.

CAUTION: Fuel supply lines are under pressure. Wear eye protection and protective gloves to avoid injuries and skin contact with fuel. Before removing from hose connection wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.







- Open threaded connection - arrow - and catch exiting fuel with a rag.

NOTE: Counterhold hex bolt of fuel distributor to release bolt. Tightening torque: 22 Nm.







- Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/12 to fuel supply line.
- Connect hose V.A.G 1318/16 onto adapter V.A.G 1318/11 of pressure gauge V.A.G 1318 and hold it in a measuring container.
- Open shut-off valve of pressure gauge V.A.G 1318. Lever will point in direction of flow - A -.
- Remove cover in front of fuse holder.







- Pull fuse No. 28 from fuse holder.
- Connect remote control V.A.G 1348/3A with adapter cable V.A.G 1348/32 to contact 28a to fuel pump and battery positive (+)
- Operate remote control V.A.G 1348/3A. Slowly close shut-off tap, until pressure gauge shows 4 bar. From this point on do not move position of shut-off tap.
- Empty measuring container.
- Delivery rate of Fuel Pump (FP) is dependent on battery voltage. Therefore, connect multimeter to vehicle battery using adapter cables from connector test kit V.A.G 1594 A.
- Operate remote control for 30 seconds and measure battery voltage.







- Compare quantity of fuel delivered with specification.
- *)Minimum delivery rate cubic cm/30 s
- **)Voltage at fuel pump with engine off and pump running (approx. 2 Volts less than battery voltage).

Example: During the test, a voltage of 12.2 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 of 550 cubic cm/30 s.

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







- Pull supply hose -1- from inlet to fuel filter.
- Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/10 to hose.
- Repeat delivery rate check.

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

If the minimum delivery rate is again not attained:
- Remove fuel delivery unit and check fuel strainer for soiling.

Only when up to now no malfunction has been detected:
- Fuel Pump (FP) faulty, replace fuel delivery unit.

Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply, for example sporadic loss of fuel supply:
- Check current draw of fuel pump as follows:
- Reconnect all disconnected fuel lines.
- Remove luggage compartment floor cover.
- Remove cover from Fuel Pump (FP).







- Connect current probe multimeter V.A.G 1715 or vehicle diagnostic, testing, and information system VAS 5051 to wire of 4-pin connector, terminal 1. arrow -.
- Start engine and run at idle speed.
- Measure current draw of fuel pump.
- Specification: max. 8 amps.

NOTE: If malfunction in fuel system is sporadic, test can also be performed during a road test, but a second person is required.

If the current draw is exceeded:
- Fuel Pump (FP) faulty, replace fuel delivery unit.

Fuel Pump (FP) check valve, checking

Conditions
- Remote control V.A.G 1348/3A connected
- Pressure gauge V.A.G 1318 connected to fuel supply hose from fuel supply line

Work sequence

NOTE: This test also checks the connections of the fuel supply line from fuel delivery unit to connection point of pressure gauge V.A.G 1318 for proper seal.







- Close pressure gauge shut-off valve (lever perpendicular to direction of flow, position - B -).
- Operate remote control at short intervals, until a pressure of approx. 4 bar has built up.

CAUTION: Danger of spray when opening shut-off valve. Hold container in front of open connection on pressure gauge.

- If pressure builds up too high, lower excess pressure by carefully opening shut-off tap.
- Watch pressure drop on gauge.
- After 10 minutes pressure must not drop below
- Engine cold: 2.2 bar Engine hot: 3.0 bar

If the pressure drops further:
- Check line connections for leaks.

If no fault is detected in the wiring:
- Fuel Pump (FP) faulty, replace fuel delivery unit.