Checking fuel delivery quantity

WARNING: This page is about a different variant/trim than selected.

Test requirements

Voltage supply OK
V.A.G 1348/3A remote control is still connected.

Test sequence

Remove fuel filler cap from fuel filler tube.

Fig 1: Identifying Supply Line And Return Line

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Disconnect supply line -1- (with white marking) and catch escaping fuel using a rag.

NOTE: Depress buttons on hose connections to do so.

WARNING:

The fuel or fuel lines in fuel system can become very hot (danger of scalding)!
In addition, the fuel system is under pressure! Before opening the system, place rags around the connection area and release pressure by carefully loosening the connection!
Wear protective goggles and protective gloves when working on the fuel system!

Fig 2: Connecting VAG 1318 Components To Fuel Supply Line

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Connect pressure gauge (V.A.G 1318) to fuel supply line using adapters (V.A.G 1318/23 and V.A.G 1318/17).
Connect hose adapter (V.A.G 1318/16) to adapter (V.A.G 1318/11) of pressure gauge and hold into measuring container.
Open shut-off valve of pressure gauge. Lever will point in direction of flow -A-.
Operate remote control. Slowly close shut-off valve until on pressure gauge

3 bar positive pressure

is indicated. Do not change position of shut-off valve any more.

Empty measuring container.
Delivery rate of Fuel Pump (FP) is dependent on battery voltage. Therefore, connect multimeter to vehicle battery using adapter cables.
Operate remote control

30 seconds

long and measure battery voltage.

Vehicles with engine codes AFP and BDF

Fig 3: Fuel Delivery Rate Graph

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Compare fuel quantity pumped with specified value.

*) Minimum delivery rate cm3/30 s

**) Voltage at Fuel Pump (FP) with engine off and pump running (approx. 2 volts less than battery voltage).

Read-out example:

During test, a voltage of 12.2 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 cm3/30 s.

Vehicles with engine code BJS

Fig 4: Fuel Delivery Chart

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Compare fuel quantity pumped with specified value.

*) Minimum delivery rate cm3/30 s

**) Voltage at Fuel Pump (FP) with engine off and pump running (approx. 2 volts less than battery voltage).

Read-out example:

During test, a voltage of 13.0 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 1, 100 cm3/30 s.

Continuation for all vehicles

If minimum delivery rate is not obtained:

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

Fig 5: Connecting Pressure Gauge VAG 1318 To Hose With Adapter VAG 1318/17 To Fuel Filter

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Disconnect supply line -1- from fuel filter input.

NOTE: Depress buttons on hose connections to do so.

Connect pressure gauge (V.A.G 1318) with adapter (1318/17) to hose.
Repeat test of delivery quantity.

If minimum delivery rate is obtained now:

Replace fuel filter:

Vehicles with engine codes AFP and BDF. Refer to Fuel tank with attachments and fuel filter (vehicles with engine code AFP and BDF), removing and installing , item 22,
Vehicles with engine code BJS. Refer to Fuel tank with attachments and fuel filter (vehicles with engine code BJS), removing and installing , item 27.

If minimum delivery rate is still not obtained:

Remove Fuel Pump (FP) unit (Refer to Fuel Pump (FP) unit, removing and installing ) and check filter strainer for dirt.

Only if no malfunctions have been found yet:

Fuel Pump (FP) malfunctioning, replace Fuel Pump (FP) unit. Refer to Fuel Pump (FP) unit, removing and installing , Fuel Pump (FP) unit, removing and installing.
Erase DTC memory of Engine Control Module (ECM). Refer to Diagnostic mode 4: Reset/erase diagnostic data
Generate readiness code. Refer to Readiness code, generating

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:
Reconnect all disconnected fuel lines.

Fig 6: Multimeter V.A.G 1715 Connected To Wire For Contact 1Of 4-Pin Connector Using Current Pick-Up Clamp.

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Connect multimeter with electrical current probe to wire of 4-pin connector (terminal 1 arrow) from wiring harness.
Start engine and let run at idle.
Measure Fuel Pump (FP) current draw.

Specified value: max. 8 amperes

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 pick-up is exceeded:

Fuel Pump (FP) malfunctioning, replace Fuel Pump (FP) unit. Refer to Fuel Pump (FP) unit, removing and installing , Fuel Pump (FP) unit, removing and installing.
Erase DTC memory of Engine Control Module (ECM). Refer to Diagnostic mode 4: Reset/erase diagnostic data
Generate readiness code. Refer to Readiness code, generating