Cayenne GTS (9PA) V8-4.8L (2008)
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Fuel Pressure: Testing and Inspection
Checking Fuel Pressure (Low Pressure) On DFI Engines
Checking Fuel Pressure (Low Pressure) On DFI Engines
Tools
Checking fuel pressure (low pressure) on DFI engines using the PIWIS Tester
INFORMATION:
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Faults in the fuel high-pressure injection system are often caused by defects in the pre-delivery system (fuel low pressure).
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In the event of problems in the fuel high-pressure injection system, the pre-delivery system must be checked first.
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The latest version of the procedure for checking the low-pressure area can be found under Guided Fault Finding on the PIWIS Tester.
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The fuel delivery pressure (low pressure) can only be measured during a test drive when a pressure gauge is connected. When you drive the
vehicle, only the measured value Fuel high pressure actual value can be read out with the PIWIS Tester in the DME (DFI) control unit via the
high-pressure sensor. There is no "low pressure" actual value. This must be checked with the engine running or during a journey using a pressure
gauge.
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If you suspect that the pumps in the fuel tank are defective (particularly if symptoms include a very low fuel level), always check the sucking jet
pumps for dirt or blockages. A piping diagram and assembly overview are shown in the information section for the fuel pumps.
Strategy for fuel pump operation
The fuel pumps in the tank are activated differently depending on the fuel level in the tank and the load.
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Both fuel pumps are activated when you start the engine and for up to 10 seconds afterwards.
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Fuel pump 2 (right) is always activated if the fuel level in the tank is > 60 litres.
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Fuel pump 1 (left) is always activated if the fuel level in the tank is > 15 litres and < 60 litres.
