Fuel Pressure And Residual Pressure Before High Pressure Pump, Checking

WARNING: This page is about a different car, the 2012 Audi Q5, 2011 Audi Q5, 2010 Audi Q5, and 2009 Audi Q5. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and workshop equipment required

Pressure Gauge K-Jetronic VAS1318
Pressure Gauge Adapter VAS1318/10-12
Connector Test Set VAS1594C
Remote Control VAS1348/3A with Adapter Cable VAS1348/3-3
Measuring container, fuel-resistant
Protective gloves

Fuel Pressure, Checking

Battery voltage at least 12.5 Volts.
Fuel filter OK.
Fuel tank at least ¹ /₄ filled.
Fuel Pump (FP) control module -J538- OK.
Ignition turned off.

Fuel Pressure, Checking

-- Remove rear seat bench. Refer to REAR SEAT, REMOVING AND INSTALLING .

-- Remove locking flange cover -arrows-.

Fig 1: Identifying Cover Bolts For Locking Flange

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-- Disconnect electrical harness connector -1- at locking flange.

Fig 2: Identifying Locking Flange Components

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NOTE:

Ignore -2-.

-- Connect VAS1348/3A with VAS1348/3-3 with an adapter cable from the VAS1594C at terminal -1-.

-- Using insulating tape, tape over the second terminal on the VAS1348/3-3 -arrow- to prevent a short circuit.

Fig 3: Checking Fuel Pressure

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-- Connect terminal -5- to the vehicle ground using a jumper cable from the VAS1594C.

-- Connect VAS1348/3A to item -A- in the terminal box in the plenum chamber (battery +). For safety reasons, install a fuse (10 A) in the wiring connection.

-- Route VAS1348/3A switch forward in engine compartment.

-- Remove seal -arrow-.

Fig 4: Identifying Alarm Horn, Removal

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-- Unclip plenum chamber cover -2- and remove it.

NOTE:

Ignore -1 and 3-.

-- Release retainer -arrow A- and open cover -arrow B-.

Fig 5: Opening Terminal Box Cover

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-- Connect alligator clip to the battery jump start terminal -U6- -A- in the terminal 30 wire junction 2 -TV22- in plenum chamber.

Fig 6: Checking Fuel Pressure

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-- Remove fuel filler cap from fuel filler tube.

-- Remove front engine cover.

-- Remove fuel supply line -arrow- from the high pressure pump.

Fig 7: Identifying Fuel Supply Hose

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WARNING:

There is a risk of injury because the fuel is under high pressure.

To reduce pressure in fuel system, lay a clean cloth around the connector and carefully loosen connector.

-- Connect VAS1318 to the fuel supply line using an adapter.

Fig 8: Bleeding Fuel System

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-- Connect an assisting hose -arrow- to pressure gauge and hold it in a measuring container.

-- Open shut-off valve of pressure gauge.

The lever points in the direction of flow.

-- Bleed fuel system by pressing remote control briefly.

-- Close shut-off valve of pressure gauge.

Fig 9: Closing Pressure Gauge Cut-Off Valve

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Lever stands perpendicular to direction of flow -arrow-.

-- Hold the switch of the remote control until no more pressure increase is observed on the fuel pressure gauge.

Specified value: Approximately 5.5 bar (4.5 to 6.5 bar) positive pressure.

If specification is not obtained:

-- Check delivery quantity of Fuel Pump (FP). Refer to FUEL, CHECKING DELIVERY QUANTITY, VEHICLES WITH 3.2L FSI ENGINE .

Residual Pressure, Checking

-- Check for leaks and residual pressure by observing pressure drop on pressure gauge.

After 10 minutes there must be a residual pressure of at least 3 bar.

If residual pressure drops below 3 bar:

Check connection between fuel pressure gauge and fuel line for leaks.
Check pressure gauge for leaks.
Check fuel lines and their connections for leaks.
Check delivery quantity of Fuel Pump (FP). Refer to FUEL, CHECKING DELIVERY QUANTITY, VEHICLES WITH 3.2L FSI ENGINE .
Replace fuel filter with integrated fuel pressure regulator. Refer to FUEL FILTER, REMOVING AND INSTALLING, VEHICLES THROUGH MY 2012 or FUEL FILTER, REMOVING AND INSTALLING, VEHICLES FROM MY 2013 .
Fuel pump check-valve is faulty. Refer to FUEL PRESSURE AND RESIDUAL PRESSURE, CHECKING, VEHICLES WITH 3.2L FSI ENGINE .

Assembly is in the reverse order of removal, note the following:

-- Switch off ignition.

NOTE:

Before removing pressure gauge, release fuel pressure by opening shut-off valve. Hold a container under the connection.

-- Connect fuel supply line -arrow- to the high pressure pump.

Fig 10: Identifying Fuel Supply Hose

Courtesy of AUDI OF AMERICA, LLC

NOTE:

Check fuel system for leaks.