Checking delivery rate

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Test conditions

Voltage supply OK.
Remote control V.A.G 1348/3A connected

Test sequence

Remove fuel filler cap from fuel filler tube.

CAUTION: Fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before removing from hose connection wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

Fig 1: Identifying Supply Line And Return Line

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

Fig 2: Pressure Gauge V.A.G 1318 Connections (1 Of 2)

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Connect pressure gauge V.A.G 1318 with double connection V.A.G 1318/23 and adapter set V.A.G 1318/17 to fuel supply line.
Connect adapter V.A.G 1318/1 to 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 -.
Operate remote control for VAG 1348 V.A.G 1348/3A. Slowly close shut-off tap, until pressure gauge shows 3 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 1594C.
Operate remote control for 30 seconds and measure battery voltage.

Fig 3: Fuel Delivery Rate Graph

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Compare quantity of fuel delivered with specification.

*) Minimum delivery rate cm ³ /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 12.5 volts is measured at the battery. Since voltage at the pump is approx. 2 Volts less than battery voltage, there is a minimum delivery rate of 200 cm ³ /30 s.

If minimum delivery rate is not attained:

Check fuel lines for possible restrictions (kinks) or blockages.

Fig 4: Pressure Gauge V.A.G 1318 Connections (2 Of 2)

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Pull supply hose - 1 - from inlet to fuel filter.
Connect Pressure Gauge V.A.G 1318 with Adapters V.A.G 1318/17 to fuel supply line.
Repeat delivery rate check.

If minimum delivery rate is now obtained:

Replace fuel filter:

If minimum delivery rate is again not obtained:

Remove fuel delivery unit and check filter strainer for dirt.

Only when up to now no malfunction has been detected:

Fuel Pump (FP) faulty, replace fuel delivery unit refer to Fuel delivery unit, removing and installing .
Check DTC memory.
Read readiness code.
If DTC memory was cleared or engine control module disconnected from voltage supply, readiness code must be regenerated.

Delivery rate has been obtained, but malfunctions are still suspected in fuel supply, for example sporadic loss of fuel supply:

Check current draw of fuel pump as follows:
Reconnect all disconnected fuel lines.

Fig 5: Measuring Current Draw Of Fuel Pump Using VAG 1715

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Connect Multimeter V.A.G 1715 with current clamp to wire for 4-pin connector terminal 1 - arrow - on wiring harness.
Start engine and run at idle speed.
Measure current draw of fuel pump. Specified value: 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 current draw is exceeded:

Fuel Pump (FP) faulty, replace fuel delivery unit refer to Fuel delivery unit, removing and installing .
Check DTC memory.
Read readiness code.
If DTC memory was cleared or engine control module disconnected from voltage supply, readiness code must be regenerated.