Checking Residual Pressure:

WARNING: This page is about a different car, the 2012 Audi S5, 2011 Audi S5, 2010 Audi S5, 2009 Audi S5, and 2008 Audi S5. However, it is still accessible from the selected car via links, so may be relevant.

-- 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 The 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 the fuel pump delivery quantity. Refer to DIAGNOSIS AND TESTING .
Replace the fuel filter with the integrated fuel pressure regulator. Refer to REMOVAL AND INSTALLATION .
Fuel pump check-valve is faulty. Refer to DIAGNOSIS AND TESTING .

Assembly is in 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.

-- Install The Fuel Supply Line On The Distribution Piece. Make Sure It Is Clean And There Are No Leaks.