A6 Quattro Sedan V6-2.7L Turbo (APB) (2000)
With engine cold: at least 2.2 bar
With engine at operating temperature: approx.: 3.0 bar
NOTE: A rise the pressure (due to fuel expansion) when the engine is at operating temperature is normal.
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Start the engine and run at idling speed.
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Switch ignition off after the pressure has built-up. At the same time close pressure gauge cut-off tap (lever at 90° to through flow direction).
If the pressure does not drop, the following faults are possible:
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Union between pressure gauge and fuel supply pipe leaking
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Supply pipe leaking at fuel tank
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Return valve in fuel pump leaking
NOTE: When the cut-off tap is closed the pressure gauge will indicate the pressure downstream of the cut-off tap, i.e. on the same side as the intake
manifold, injectors and fuel pressure regulator. If there is then a drop in pressure upstream of the cut-off tap (same side as fuel tank), the change will not
be registered by the pressure gauge. This is why the paragraph beginning of the pressure does not drop... " has been included above.
If the pressure drops again, the following malfunctions are possible:
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Fuel pressure regulator faulty
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Fuel Injectors leaking
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Unions on pressure gauge downstream of cut-off valve leaking
NOTE: When disconnecting the pressure gauge, close the cutoff valve, unscrew the union on adapter VAG 1318/15, then open the cut-off valve to
drain off excess fuel into a suitable container.