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‒ → Pull vacuum hose -arrow- off fuel pressure regulator.
- The fuel pressure must increase to approx. 4.0 bar.
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‒ Reconnect vacuum hose.
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‒ Switch off ignition.
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‒ Observe pressure drop on gauge.
- After 10 minutes the remaining pressure should be at least 2.5 bar.
If the holding pressure drops below 2.5 bar:
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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 throughflow direction).
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‒ Observe pressure drop on gauge.
If the pressure does not drop, the following faults are possible:
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◆ Fuel pressure regulator defective
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◆ Injectors leaking
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◆ Unions on pressure gauge downstream of cut-off valve leaking
If the pressure drops again, 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
=> 4-cylinder Engine, Mechanics; Repair Group 20; Removing and installing fuel pump
Note:
When disconnecting the pressure gauge, close the cut-off valve, unscrew the union on adapter V.A.G 1318/12, then open the cut-off valve to drain off excess fuel into a suitable container.
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