Checking Delivery Quantity, Current Pick-Up, And Check Valves Of Fuel Pumps (FP)

Test requirement

Function and voltage supply of fuel pumps OK

Fig 1: Identifying Special Tools -- Checking Delivery Quantity, Current Pick-Up, And Check Valves Of Fuel Pumps (FP) (1 Of 2)

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Special tools and workshop equipment required

Wrench T10202
Remote control VAG1348/3A with adapter cable VAG1348/3-3
Pressure gauge VAG1318
Adapter VAG1318/7
Adapter VAG1318/13
Adapter VAG1318/17

Fig 2: Identifying Special Tools -- Checking Delivery Quantity, Current Pick-Up, And Check Valves Of Fuel Pumps (FP) (2 Of 2)

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Special tools and workshop equipment required

Torque wrench (5 to 50 Nm) VAG1331
Torque wrench (40 to 200 Nm) VAG1332
Connector test kit VAG1594A
Multimeter VAG1715

Without illustration:

Measuring container
Wiring diagram

Checking fuel delivery

-- Remove fuel filler cap from fuel filler tube.

First, reduce fuel pressure as follows:

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!

-- Place a rag around separating point to catch escaping fuel.

Fig 3: Identifying Fuel Supply Line

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-- Remove fuel supply line (arrow).

When the fuel pressure is reduced:

-- Tighten threaded connection again.

Checking fuel delivery:

Fuel Pump (FP) -G6-, right,
Transfer Fuel Pump (FP) -G23-, left,
Fuel Pumps (FP) left and right.

Supply quantity of Fuel Pump (FP) -G6-, right, checking

-- Connect remote control VAG1348/3A to connector (arrow) of Fuel Pump (FP) relay for right Fuel Pump (FP) using adapter VAG1348/3-3.

Fig 4: Connecting V.A.G 1348/3A Remote Control To Connector Of Fuel Pump (FP) Relay For Right Fuel Pump (FP) Using V.A.G 1348/3-3 Adapter

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-- Connect alligator of remote control to B+ connection -1-.

Fig 5: Connecting Alligator Of Remote Control To B+ Connection

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-- Disconnect fuel supply line -1- from fuel distributor.

Fig 6: Disconnecting Fuel Supply Line From Fuel Distributor

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-- Place hose in a measuring container -2- of at least 1000 cm³ .

-- Measuring container must be emptied before measurement.

-- Operate remote control

15 seconds: a minimal delivery quantity of

800 cm³ /15 seconds must be obtained.

Supply quantity of Transfer Fuel Pump (FP) -G23-, left, checking

-- Connect remote control VAG1348/3A to connector (arrow) of Fuel Pump (FP) relay for left Fuel Pump (FP) using adapter VAG1348/3-3.

Fig 7: Checking Delivery Quantity Of Left Pump

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-- Connect alligator of remote control to B+ connection -1-.

Fig 8: Connecting Alligator Of Remote Control To B+ Connection

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-- Disconnect fuel supply line -1- from fuel distributor.

Fig 9: Disconnecting Fuel Supply Line From Fuel Distributor

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-- Place hose in a measuring container -2- of at least 1000 cm³ .

-- Measuring container must be emptied before measurement.

-- Operate remote control

15 seconds: a minimal delivery quantity of

800 cm³ /15 seconds must be obtained.

Supply quantity of both Fuel Pumps (FP), checking

-- For this, now connect adapter VAG1348/3-3 of remote control to connector of Fuel Pump (FP) Relay, left and right:

Connector (arrow) of Fuel Pump (FP) Relay for right Fuel Pump (FP).

Fig 10: Connecting V.A.G 1348/3A Remote Control To Connector Of Fuel Pump (FP) Relay For Right Fuel Pump (FP) Using V.A.G 1348/3-3 Adapter
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Connector (arrow) of Fuel Pump (FP) Relay for left Fuel Pump (FP).

Fig 11: Checking Delivery Quantity Of Left Pump
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-- Connect alligator of remote control to B+ connection -1-.

Fig 12: Connecting Alligator Of Remote Control To B+ Connection

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-- Disconnect fuel supply line -1- from fuel distributor.

Fig 13: Disconnecting Fuel Supply Line From Fuel Distributor

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-- Place hose in a measuring container -2- of at least 1000 cm³ .

-- Measuring container must be emptied before measurement.

-- Operate remote control

10 seconds: a minimal delivery quantity of

800 cm³ /10 seconds must be obtained.

If the minimal delivery quantity is not obtained during one of the tests:

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

If the lines are OK:

-- Replace filter element in fuel filter.

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply (e.g. sporadic loss of fuel supply):

-- Check current pick-up of Fuel Pumps (FP)

Checking current pick-up of Fuel Pumps (FP)

Check current pick-up of each individual Fuel Pump (FP) as follows:

-- Re-connect all disconnected fuel lines.

-- Cut through floor carpet from point -A- to point -B- in pre-cut area (arrows).

Fig 14: Identifying Carpet Cutting Area

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-- Unscrew nuts -1- of cover. Remove backrest support -2- or mounting bracket if necessary.

Fig 15: Identifying Nuts, Cover, And Anchor Plate

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-- Connect multimeter with electrical current probe to wire of 4-pin connector terminal -1- (arrow) from wiring harness to Fuel Pump (FP), right.

Fig 16: Connecting Current Clamp Of Multimeter To Wire Of 4-Pin Connector Contact From Wiring Harness To Right Fuel Delivery Unit

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-- Start engine and let run at idle.

-- Measure Fuel Pump (FP) current draw.

Specified value: max. 11 amperes

If current draw is exceeded:

-- Fuel Pump (FP), right, faulty, replace Fuel Pump (FP) unit, Fuel Pump (FP) unit, fuel gauge sender, and suction jet pumps, removing and installing.

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

-- Repeat test on Fuel Pump (FP), left.

If current draw is exceeded:

-- Fuel Pump (FP), left, faulty, replace Fuel Pump (FP) unit, Fuel Pump (FP) unit, fuel gauge sender, and suction jet pumps, removing and installing.

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

NOTE:

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