Engine Codes AEG, AVH, AZG, BEV

Fig 1: Identifying Special Tools - Fuel Pump, Checking (Engine Codes AEG, AVH, AZG, BEV)

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Special tools, testers and auxiliary items required

Union nut spanner 3217
Pressure gauge VAG 1318
Adapter VAG 1318/11
Hose adapter VAG 1318/16
Adapter VAG 1318/17
Adapter VAG 1318/23
Adapter VAG 1318/1

Fig 2: Identifying Special Tools - Fuel Pump, Checking (Engine Codes AEG, AVH, AZG, BEV, BBW)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Special tools, testers and auxiliary items required

Torque wrench (40 to 200 Nm) VAG 1332
Remote control VAG 1348/3A with adapter cable VAG 1348/3-2
Test system VAG 1466 A
Diode test lamp VAG 1527 B
Adapter set VAG 1594 A
Multimeter VAG 1715 or Fluke 83 Multimeter
Measuring container
Wiring diagram

Requirements

Fig 3: Identifying Main Fuse Panel

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Fuse No. 28 OK.
Battery voltage must be at least 11.5 V.
All electrical consumers, e.g. lights and rear window defroster, must be switched off.
If the vehicle is equipped with air conditioning, this must be switched off.

On models with an automatic transmission the selector lever must be in position "P" or "N".

NOTE:

Observe description of crash fuel shut-off function. Refer to Crash Fuel Shut-off under Crash fuel shut-off .

Checking Function and Voltage Supply

Remove cover from fuel delivery unit.
Briefly operate starter. Fuel pump must be heard to run
Switch off ignition.

If fuel pump does not run:

Remove cover in front of fuse holder.

Fig 4: Connecting VAG 1348/3A With Adapter Cable VAG 1348/3-2 To Contact And Battery Positive

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Pull fuse No. 28 out of fuse holder.
Connect remote control VAG 1348/3A with adapter cable VAG 1348/3-2 to contact 28a to fuel pump and battery positive (+).
Operate remote control.

Fuel pump runs:

Check activation of fuel pump relay referring to wiring diagram: Refer to Electrical Wiring Diagrams, Troubleshooting and Component Locations

Fuel pump does not run:

Fig 5: Fuel Delivery Connector

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Take 4-pin connector off flange - arrow -.

Fig 6: Connecting Diode Test Lamp VAG 1527 B With Auxiliary Cables From VAG 1594 A To Outer Contacts Of Connector

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Connect diode test lamp VAG 1527 B with auxiliary cables from VAG 1594 A to outer contacts of connector.
Operate remote control. LED must light up

If LED does not light up:

Locate and eliminate open circuit using current wiring diagram: Refer to Electrical Wiring Diagrams, Troubleshooting and Component Locations

LED lights up (voltage supply OK.):

Fig 7: Removing/Installing Union Nut With Wrench 3217

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Remove union nut with wrench 3217
Check electrical wiring between flange and fuel pump for continuity.

If no open circuit can be found:

Fuel pump is faulty, replace fuel delivery unit. Refer to Fuel Delivery Unit, Removing and Installing under Fuel delivery unit, removing and installing

Checking Delivery Rate

Requirements

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

Work Sequence

Remove filler cap from fuel tank filler neck.

CAUTION:

The fuel system is under pressure! Before opening the system place a cloth around the connection. Then release the pressure by carefully loosening the connection.
Always wear eye protection and wear fuel-resistant gloves when disconnecting system connections.

Engine Codes AEG, AVH, AZG

Fig 8: Identifying Vacuum Hose To Throttle Valve Control Module, Fuel Return Hose & Fuel Supply Hose (AEG, AVH, AZG)

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Pull off supply hose - 3 - (with white marking) and collect fuel which leaks out in a cloth.

NOTE:

To disconnect, press buttons on hose couplings

Engine Code BEV

Fig 9: Identifying Fuel Return Hose & Fuel Supply Hose (Engine Code BEV)

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Pull off supply hose - 1 - (with white marking) and collect fuel which leaks out in a cloth.

NOTE:

To disconnect, press buttons on hose couplings.

All Engines

Fig 10: Connecting VAG 1318 Components To Fuel Supply Line

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Connect pressure gauge VAG 1318 with adapter VAG 1318/23 and adapter VAG 1318/17 to fuel supply line.
Push hose adapter VAG 1318/16 onto adapter VAG 1318/11 on pressure gauge and hold hose in a measuring container.
Open shut-off tap on pressure gauge. Lever then points in direction of flow - A -.
Operate remote control VAG 1348/3A. Then close shut-off tap slowly until pressure gauge shows 3.5 bar pressure. From this point on do not alter setting of shut-off tap. Engine code BEV: approx. 3.5 bar
Empty measuring container.
Quantity of fuel delivered by fuel pump depends on battery voltage. Therefore connect multimeter to vehicle battery using adapter cables from VAG 1594 A.
Operate remote control for 30 seconds and measure battery voltage.

Fig 11: Fuel Delivery Chart (Engine Codes AEG, AVH, AZG, BEV)

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Compare quantity of fuel delivered with specification.

*) - Minimum delivery cm ³ /30 seconds

**) - Voltage at fuel pump with engine at rest 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. As the voltage at the pump is approx. 2 volts less than the battery voltage, the result is a minimum delivery of approx. 200 cm ³ /30 seconds.

If the minimum delivery rate is not attained:

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

Fig 12: Connecting Pressure Gauge VAG 1318 To Hose With Adapter VAG 1318/17 To Fuel Filter

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Disconnect supply hose - 1 - from inlet to fuel filter.

NOTE:

To disconnect, press buttons on hose couplings

Connect pressure gauge VAG 1318 to hose with adapter VAG 1318/17.
Repeat delivery rate check.

If minimum delivery rate is now attained:

Replace fuel filter

If minimum delivery rate is again not attained:

Remove fuel delivery unit and check filter strainer for soiling.

Up to now no fault has been detected:

Fuel pump faulty, replace fuel delivery unit. Refer to Fuel Delivery Unit, Removing and Installing under Fuel delivery unit, removing and installing .

If delivery quantity has been attained, but nevertheless a fuel supply system fault is suspected (e.g. intermittent failure of fuel supply system):

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

Fig 13: Measuring Current Draw Of Fuel Pump Using VAG 1715

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Connect multimeter VAG 1715 using current clamp to green/yellow wire of wiring harness.
Start engine and run at idle speed
Measure current draw of fuel pump. Specification: max. 8 amps.

NOTE:

If the fuel system malfunction is intermittent, the check can be performed during a road test, but a 2nd technician is necessary.

If current consumption is exceeded:

Fuel pump faulty, replace fuel delivery unit. Refer to Fuel Delivery Unit, Removing and Installing under Fuel delivery unit, removing and installing .

Checking Fuel Pump Non-return Valve

Requirements

Remote control VAG 1348/3A is still connected
Pressure gauge VAG 1348 is still connected

With this check the fuel supply line connections from fuel delivery unit to the point at which the pressure gauge VAG 1318 is connected will be checked for leaks at the same time.

Fig 14: Connecting VAG 1318 Components To Fuel Supply Line

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Close pressure gauge shut-off tap (lever at right angles to through flow direction position - B - ).
Operate remote control at short intervals until a pressure of approx. 3 bar has built up.

CAUTION: Danger of spray when opening the shut-off trap, hold container before connecting of pressure gauge.

If pressure builds-up too high, relieve excess pressure by carefully opening shut-off tap.
Observe pressure drop on gauge. After 10 minutes, pressure must not drop below 2.5 bar.

If the pressure drops further:

Check line connections for leaks.

If no fault in lines is detected:

Fuel pump faulty, replace fuel delivery unit. Refer to Fuel Delivery Unit, Removing and Installing under Fuel delivery unit, removing and installing .