S4 V8-4.2L (BHF) (2004)
Fuel Pressure: Testing and Inspection
Fuel Pressure Regulator And Holding Pressure, Checking
NOTE: The fuel pressure regulator is found in the fuel filter under the tank.
Special tools and equipment
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V.A.G 1318 with V.A.G 1318/6 and V.A.G 1318/7
Test conditions
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Fuel pump relay OK
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Fuel pump OK
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Fuel filter OK
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Battery voltage at least 11 V
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Vehicles with automatic transmission: Selector lever set to P or N
Check pressure system
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Open the fuel tank lid briefly (pressure should drop).
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Remove engine cover.
CAUTION: The fuel system is pressurized. Before loosening hose connections or opening the test connection (to measure fuel pressure), place a
cloth around the connection. Then release pressure by carefully loosening the connection.
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Use cloth to cover union (subject to fuel pressure).
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Remove fuel hose from fuel rail pipe connection.. To do so, counterhold using an open-end wrench at each hex head -1- and -3- and remove union
nut -2-.
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Unscrew pressure gauge V.A.G 1318 with adapters V.A.G 1318/6, 1318/7 between supply line and fuel rail.
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Open pressure gauge cut-off valve. Lever points in direction of flow.
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Start engine and run at idling speed.
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Measure fuel pressure.
Specification: approx. 3.5 bar
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Switch ignition off.
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Test for leaks and holding pressure by watching pressure drop on gauge.
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After 10 minutes the remaining pressure should be at least 2.5 bar.
If holding pressure drops below 2.5 bar: