Fuel Pressure Test (2.8L VR6, Engine Code AXK)

Ensure ignition is off. Ensure battery voltage is at least 12 volts. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE (2.8L VR6, ENGINE CODE AXK) .
Connect Pressure Gauge (VAG 1318), or equivalent, at fuel supply line/hose in engine compartment. See Fig 1 and Fig 2 . Open shut-off valve of fuel pressure gauge; lever points in the direction of flow. Reinstall fuel pump fuse No. 18.
NOTE: Depress buttons on fuel hose connection to disconnect hose.

Fig 1: Locating Fuel Supply Line Connection (2.8L VR6, Engine Code AXK)
Courtesy of VOLKSWAGEN UNITED STATES, INC.

Fig 2: Connecting Fuel Pressure Gauge (2.8L VR6, Engine Code AXK)
Courtesy of VOLKSWAGEN UNITED STATES, INC.
Start engine and idle. Fuel pressure should be within specification. See FUEL PRESSURE SPECIFICATIONS (2.8L VR6) table. If fuel pressure is as specified, go to next step. If fuel pressure is NOT as specified, check fuel pump volume. See FUEL PUMP VOLUME CHECK .
Continue to idle engine. Disconnect vacuum line from fuel pressure regulator, see Fig 3 . For specification, see FUEL PRESSURE SPECIFICATIONS (2.8L VR6) table.

Fig 3: Disconnecting Fuel Pressure Regulator Vacuum Hose (2.8L VR6, AXK)
Courtesy of VOLKSWAGEN UNITED STATES, INC.
If fuel pressure is not as specified, check fuel pump volume. See FUEL PUMP VOLUME CHECK . If fuel volume is okay, go to next step.
Perform fuel system residual pressure test. Reinstall vacuum hose on fuel pressure regulator and continue to run engine at idle. Turn engine off.
Check residual fuel pressure after 10 minutes. See FUEL PRESSURE SPECIFICATIONS (2.8L VR6) table.
If residual pressure drops below specification, restart engine and let it idle.
When fuel pressure has built up, turn off ignition. At the same time, close shut-off valve on Pressure Gauge (VAG 1318). Lever will be at 90 degrees to fuel flow. See Fig 4 . Check residual fuel pressure again.

Fig 4: Fuel Pressure Test Gauge (Lever In Closed Position)
Courtesy of VOLKSWAGEN UNITED STATES, INC.
If residual fuel pressure does not drop, test for faulty fuel pump check valve. See FUEL PUMP CHECK VALVE . If residual fuel pressure drops again, check pressure gauge for leaks. Check for leaking fuel lines and connections. If no leaks are found, turn off ignition. Check for leaking fuel injectors or fuel pressure regulator.

NOTE: To test for leaking fuel injectors, see FUEL INJECTOR TESTS under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING article.