Checking Fuel Pressure - Engine Stopped

→ In case of contact with skin or eyes wash immediately with plenty of warm water and acid-free soap.

→ Consult a doctor as soon as possible.

→ Wear personal protective gear when working with fuel.

→ Avoid contact with hot parts or sources of ignition.

→ Use suction to remove ignitable vapors.

→ Attach warning sign in a clearly visible position.

Information 

• The battery voltage must not fall below 12 volts during the fuel pressure check. 
• Connect a suitable battery charger. 

Tools: 

Fig 1: Identifying Pressure Gauge Tool

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

1. Pressure gauge from K-Jetronic Tester VAG. 1318 WE 1291 
2. Connection line no. 17 (long) from VAG 1318
3. Plug-in coupling for fuel line from the fuel tank
4. Connection line P 378 C
5. Connection line no. 17 (short) from VAG 1318
6. Plug-in coupling for fuel line to the engine

1. Joining socket on pressure gauge for connection line B (item 1)
2. Joining socket on pressure gauge for connection line D (item 2)
3. Screw socket for screwing on connection lines D and E

Alternative tool (can only be used when the engine is stopped): 

Fig 2: Identifying Pressure Gauge And Connection Line

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

1. Pressure gauge 378a
2. Connection line no. 17 from VAG 1318
3. Plug-in coupling for fuel line from the fuel tank

1. PIWIS Tester 9718  must be connected to the adapter line at the input socket in the passenger compartment and ignition must be switched on.
   1. 1.1. Switch on the Tester and select the relevant vehicle.
      Fig 3: PIWIS Tester Start Page Screen Display

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
2. Run the individual control unit search for DME  .
   1. 2.1. To do this, select DME and press [F12>>].
      Fig 4: Control Unit Search Screen Display

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
3. After running the individual control unit search for DME, select Special functions  .
   Fig 5: Special Functions Menu Item Screen Display

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.
   1. 3.1. Select the menu item Drain tank  .
      Fig 6: Drain Tank Function Screen Display

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
4. Open the retaining clip for the fuel lines -1-  on the underbody and unclip the supply line.
   1. 4.1. To do this, open the clip -arrow-  using a small screwdriver.
      Fig 7: Opening Retaining Clip On Fuel Lines

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
5. Open the rapid-action coupling on the fuel pressure line -1-  .
   1. 5.1. Wrap a cloth around the connection point (to prevent splashes), press the two locking lugs and pull the line apart.

      Alternatively, relieve the fuel pressure. To do this, remove the fuse for the fuel pump, start the engine and leave it running until it stops.

      Fig 8: Identifying Plug Coupling On Fuel Pressure Line

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
6. Connect special tool test pressure gauge with lines from K-Jetronic Tester VAG. 1318 WE 1291  to the fuel lines.
   1. 6.1. Engage pressure gauge on the transmission bracket using the chain.
   2. 6.2. Insert connection lines into the relevant couplings.
      1. Pressure gauge
      2. Connection line no. 17 (short) from VAG 1318 and P 378 C fitted on line to the engine
      3. Connection line no. 17 (long) from VAG 1318 fitted on line to the fuel tank
         Fig 9: Inserting Connection Lines Into Relevant Couplings

         Courtesy of PORSCHE CARS NORTH AMERICA, INC.
   3. 6.3. Alternatively, the test can be performed using the Pressure Gauge 378A  .

      To do this, connect line no. 17 to the plug-in coupling for the fuel tank.

      Fig 10: Identifying Test Pressure Gauge (378A)

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
7. Activate the Drain tank (= activate fuel pump)  function on the PIWIS Tester 9718  by pressing [F8] Start.
   Fig 11: Starting Drain Tank Function Screen Display

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.
8. Read off the pressure shown on the pressure gauge.

   → Fuel pressure - engine not running: 5.0 bar+/-0.3 bar 

9. Deactivate the Drain tank  function by pressing [F8] Stop.
   1. 9.1. Then, press [F11] << a number of times to return to the start screen and switch off the Tester.
      Fig 12: Deactivating Drain Tank Function Screen Display

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
10. Holding pressure test: 

    → Pressure: 4.0 bar 

11. Disconnect test connections and remove test pressure gauge.
    1. 11.1. Connect plug-in coupling for fuel lines.
    2. 11.2. The coupling must lock with an audible click. Pull to check that the connection is secure.
12. Switch off the ignition and remove PIWIS Tester adapter lead in the vehicle.

    Information 

    • When the work is complete, check that all aids and foreign objects (e.g. cloths, tools) are removed from the engine compartment. 
13. Make sure there are no tools, foreign objects or aids left in the work area.