Fuel pressure and residual pressure before high pressure pump, checking

WARNING: This page is about a different car, the 2009 Audi A4, 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Special tools, testers and auxiliary items required

Fig 1: Identifying Pressure Gauge V.A.G 1318

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Pressure gauge K-Jetronic V.A.G 1318
Pressure gauge adapter V.A.G 1318/10-12

Fig 2: Identifying Remote Control Connection V.A.G 1348/3A

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3
Measuring container, fuel-resistant

Test conditions

Battery voltage at least 12.5 V.
Fuel filter OK.
Fuel tank at least ¹ /₄ filled.
Fuel Pump (FP) Control Module J538 OK; checking → 20 - FUEL SUPPLY SYSTEM .

Ignition switched off.

Checking fuel pressure

Sedan with front wheel drive:

Remove carpeting in luggage compartment.
Fold forward right backrest of rear seat, if necessary.

Wagon with front wheel drive:

Remove left 1/3 backrest →
- 72 - SEAT - FRAMES
- 72 - SEAT - FRAMES for BODY INTERIOR - CABRIOLET
.
Remove left side trim in luggage compartment and dirt tray →
- 70 - INTERIOR TRIM
- 70 - INTERIOR TRIM for BODY INTERIOR - CABRIOLET
.

All with front wheel drive:

Fold forward right backrest of rear seat, if necessary.
Remove luggage compartment floor trim.

Fig 3: Unbolting Cover

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove cover for locking flange - arrows -.

Fig 4: Disconnecting Electrical Harness Connector At Locking Flange

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Carefully release and disconnect electrical harness connector - arrow - at locking flange.

Vehicles with all wheel drive:

Remove rear seat bench →
- 72 - SEAT - FRAMES
- 72 - SEAT - FRAMES for BODY INTERIOR - CABRIOLET

Fig 5: Removing Cover Bolts For Locking Flange

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove cover for right locking flange - arrows -.

Fig 6: Disconnecting Electrical Harness Connector At Right Locking Flange

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Carefully release and disconnect electrical harness connector - arrow - at locking flange.

All:

Fig 7: Connecting Other End Of Hand Held Remote Starter (Jumper) To Vehicle Battery (+)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3 with an adapter cable from Connector Test Set V.A.G 1594C at terminal - 1 -.
Cover 2nd connector terminal of adapter cable V.A.G 1348/3-3 with insulating tape to prevent short circuit - arrow -.
Route Remote Control V.A.G 1348/3A switch forward in engine compartment.
Connect contact - 4 - to vehicle Ground (GND) using a self-made adapter cable.

Connect alligator clip to battery "+".

Fig 8: Removing Rear Engine Cover

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Pull rear engine cover off - arrows -.

CAUTION:

Fuel system is under high pressure! Before opening high pressure components of the fuel injection system, pressure must be relieved to residual pressure → Procedure that must be performed before opening the high-pressure fuel injection system. Pay close attention! .
Then wrap a clean rag around the connection and relieve residual pressure by carefully loosening the connection.

Fig 9: Disconnecting Fuel Line

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect fuel line - arrow -.

Fig 10: Connecting Pressure Gauge V.A.G 1318 To Fuel Line Using Adapter V.A.G 1318/11 And V.A.G 1318/12

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect Fuel Inj. Pressure Gauge-CIS V.A.G 1318 with Adapter V.A.G 1318/11 and V.A.G 1318/12 in fuel line.
Connect assisting hose - arrow - to pressure gauge and hold it in a measuring container.
Open shut-off valve of pressure gauge. The lever points in direction of flow.
Bleed fuel system, by briefly pressing remote control.

Fig 11: Locating V.A.G 1318 Shut-Off Tap

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Close shut-off valve of pressure gauge. Lever stands perpendicular to direction of flow - arrow -.
Hold switch of remote control until no more pressure increase is observed on fuel pressure gauge.

Specified value: approx. 6 bar positive pressure

If specification is not obtained:

Check delivery quantity of Fuel Pump (FP) → 20 - FUEL SUPPLY SYSTEM .

Checking residual pressure

Check for leaks and for residual pressure by observing pressure loss on pressure gauge.

After 10 minutes there must be a residual pressure of at least 3.75 bar.

The holding pressure drops below 3.75 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.
Replace fuel filter with integrated fuel pressure regulator → 20 - FUEL SUPPLY SYSTEM .

Replace fuel pump → 20 - FUEL SUPPLY SYSTEM .

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

NOTE:

Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold a container in front of connection for this.

Torque specifications

Component	Nm
Fuel line to fuel rail	28