Cayenne GTS (9PA) V8-4.8L (2008)
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2. Connect measuring tool -2- between the connection unit output -3- and the fuel supply line -1-. The stopcock is set to flow.
3. Start the engine and allow it to run at idle speed. Read the fuel pressure on the pressure gauge. The pointer on the pressure gauge may oscillate
when idling (due to the high-pressure pump switching between pressure stage and intake stage). With increased idle speed (accelerator pressed
slightly), the pointer deflection calms down. The fuel low-pressure system operates at a constant pressure of 5.5 bar. The pointer oscillates at
around this value. A measurement performed while driving by a second worker can also generate values of below 5 bar (4.5 bar) briefly at full
throttle (with turbo in particular). This is not a sign of a defect.
4. Alternatively, each individual fuel pump in the tank can also be actuated by the adapter 9479. For allocation of fuel pump relays - see wiring
diagram. Each individual fuel pump generates a constant pressure of 5.5 bar.
Checking fuel retaining pressure (low pressure)
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Engine cold
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Workshop air-conditioned to normal temperature
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Fluctuations may occur if the engine is warm or the outside temperature is high
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Fully sealed measuring tool setup
5. Same tool setup and connection as for measuring the fuel deliver pressure (see above).
6. Allow engine to run for a few minutes. Switch off engine. Check the pressure drop. Drop in fuel pressure after "ignition is switched off" is not
more than 1 bar after 1 hour. Make sure that the tool setup itself does not have any leaks (even the smallest of leaks). The fuel retaining pressure
will decrease extremely rapidly and falsify the measured result with even the tiniest leak.
Subsequent work
1. Disconnect tool and reconnect vehicle connections. Absorb and wipe off residual fuel with a cloth.
2. Fit cover plate.
3. Fit seat belt.
4. Fit rear seat.
5. Air the vehicle with the windows open.
