Fuel Pressure: Testing and Inspection

Checking Fuel Pressure And Quantity Delivered







Special tools

Item A - G:

Test conditions
- The battery voltage may not be less than 12 V during the test.
- If it is established during the delivery quantity check that the quantity delivered is too low, the measurement must be repeated on the second purge valve of the fuel gallery.
- The fuel system components must not be soiled.

Checking fuel pressure
1. Pull the cover of the throttle body vertically upwards.







2. Screw down the front right closure cap on the fuel gallery.

CAUTION:
Danger of fire and injury.
- Danger of fire due to escaping fuel, e.g. on hot engine components or due to electrostatic charge.
- Danger of fire due to naked flames and sparks, e.g. during welding or grinding work.
- Secure the vehicle, e.g. with a warning sign.
- Wear protective gloves that are fuel-resistant.
- Ensure that there is adequate ventilation or extract all fuel vapours.
- Before opening the fuel lines or fuel hoses, relieve the fuel pressure.
- Collect escaping fuel, absorb it if necessary with a suitable binding material and dispose of properly.
- Pay attention to cleanliness when working on the fuel system.
- Avoid contact with the skin and eyes.

3. Connect the connection line 9559 to the pressure gauge P378. Screw the other end of the line onto the fuel gallery.







4. Switch on the ignition and start the engine. Read off the fuel pressure on the pressure gauge. The value must be 4.0±0.2 bar at idle speed.







NOTE: The retaining pressure must be 2.0 bar greater one hour later.


5. Unscrew the connection line and close the fuel gallery with a new plastic cap.







6. Press the four rubber elements in the cover onto the four ball socket holders. The fastening elements must be felt to engage.







Checking fuel delivery quantity

1. Pull the cover of the throttle body vertically upwards.







2. Screw down the front right closure cap on the fuel gallery.

NOTE: The fuel gallery is pressurised. A cloth must be placed under the front area of the fuel gallery to prevent fuel dropping on hot engine parts.

CAUTION:
Danger of fire and injury.
- Danger of fire due to escaping fuel, e.g. on hot engine components or due to electrostatic charge.
- Danger of fire due to naked flames and sparks, e.g. during welding or grinding work.
- Secure the vehicle, e.g. with a warning sign.
- Wear protective gloves that are fuel-resistant.
- Ensure that there is adequate ventilation or extract all fuel vapours.
- Before opening the fuel lines or fuel hoses, relieve the fuel pressure.
- Collect escaping fuel, absorb it if necessary with a suitable binding material and dispose of properly.
- Pay attention to cleanliness when working on the fuel system.
- Avoid contact with the skin and eyes.

3. Connect a test hose with a measuring adapter and connect the other end to the purge valve on the fuel gallery.







NOTE: A second person must stop the time for the delivery quantity check.

4. Hang the open hose end of the pressure regulator in the measuring cup.







5. Connect jumper wire 26 with two measuring cables 16 from measurement tool set 9684 and jumper the fuel pump. The exact assignment of the contacts can be found in Fuse carriers.

NOTE: To avoid measurement errors, ensure that the hoses are filled with fuel when the test is started.

6. Switch on the fuel pump until fuel emerges from the end of the hose. Then empty the measuring cup.
7. Switch on fuel pump I (left pump) for one minute. Check the fuel that is delivered and note the quantity. Then repeat the process with pump II (right pump).

Fuel pump Quantity delivered
Fuel pump I (left) greater than 1.6 l/min
Fuel pump II (right) greater than 1.3 l/min

- If the quantity delivered for a measurement is too low, the measurement must be repeated on the right purge valve of the fuel gallery.

8. Switch off the ignition once the measuring process has been completed and remove the test tool.

DANGER:
Danger of fire.
- Install only the special valves provided by
- Porsche in the fuel gallery.
- Do not replace purge valves by tyre valves.
- The plastic cap must be replaced.

9. Press the four rubber elements in the cover onto the four ball socket holders. The fastening elements must be felt to engage.