Fuel Supply - Porsche Cayenne V6 2008 Service Information

Fuel, Exhaust & Engine Electrics
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Fuel Supply

The engine is designed to provide optimum performance and fuel
consumption if unleaded premium fuel with 93 octane (
unleaded premium fuels with a lower octane number is used, the
engine's knock controller automatically adapts the ignition timing. The
maximum filling approx. 26 Gals. (100 liters), with a reserve of approx.
3 Gals. (12 liters).
Safety
Always read and follow the safety instructions in the Technical Manual,
Group 2 when working on the fuel supply system.
> Fuel low-pressure system in DFI engines.
Technical Manual
The procedure for checking the fuel pressure and the amount of fuel
delivered by the fuel pumps is described in the Technical Manual.
• The low pressure system delivers the fuel from the fuel tank to the
high pressure pump on the cylinder head.
• The new Cayenne vehicles have a returnless fuel system (RF).
• The demand control function of the fuel delivery rate reduces fuel
heating in the tank by switching on the second fuel pump.
The fuel tank is not symmetrical. The left half of the tank has a higher
volume than the right side. There is a "hump" in the middle so that both
chambers are separated from each other once a certain fuel level is
reached in the tank. When the tank is half full, the left fuel pump is acti-
vated because the left half of the tank has the higher volume. The fuel
pumps are each supplied by one sucking jet pump whose hoses are
routed diagonally and which "helps itself" to fuel from the other half of
the tank.
The fuel pressure and the way in which the two fuel pumps are activated
has changed compared to Cayenne vehicles up to model year 2006. On
Cayenne vehicles up to M.Y. 2006, the left fuel pump was permanently
activated and the right pump was only activated as required (for
starting, higher delivery rate, etc.).
R+M ) is used. If
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