Porsche 996 TT Repair Manual page 607

• The battery voltage may not fall below 12 volts during the fuel pressure check!
1. Check the charge state of the battery, e.g. using a voltmeter or the Porsche System Tester PST 2. The
battery voltage must not fall below 12 volts during the check.
Note
• Use the brass closure cap on the test connection of the fuel pressure line only once as the sealing ring
cannot be replaced. To avoid possible leaks, the cap must be replaced after removal!
2. Release the metal cap on the test connection of the pressure pipe from the fuel filter to the fuel collection
pipe and screw it off by hand (a/f 13 mm).
3. Connect connecting lead 9559 with special tool pressure gauge P 378a (a/f 17 union nut) and manually
attach the line to the test connection of the fuel supply line −arrow− .
Procedure when the engine is standing still:
4. Connect the Porsche Tester PST 2 in the vehicle, switch on the ignition and switch off all loads,
such as the radio and air conditioning.
5. Activate fuel pump relay using Porsche System Tester. To do this, select the line drive links in the
DME control unit individual search and then select fuel pump relay −see figure− . Activate by
pressing the F8 key.
6. Read value on pressure gauge.
Target test values when engine not running: 3.8 ± 0.2 bar.
7. Switch off the fuel pump relay on the System Tester by pressing F8 .
20 02 01 Checking fuel pressure
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