High-Pressure Fuel Pump: Porsche Cayenne Models And Variants

The Porsche Cayenne is a powerful and stylish SUV, but like any car, it may encounter some problems as it ages. One common issue that Cayenne owners may experience is a defective high-pressure fuel pump (HPFP). The HPFP plays a crucial role in the Cayenne's returnless fuel system, which adjusts low-pressure fuel delivery to match the engine's needs. When the HPFP fails, it can cause a range of issues, from reduced engine performance and warning lights to the car stalling or even giving up while driving. In this article, we will discuss the signs of a faulty HPFP, the potential dangers, and the steps to replace it. We will also provide valuable tips to ensure a safe and effective repair process, helping Cayenne owners get their beloved vehicles back to their best condition.

The high-pressure fuel pump is in addition to the regular fuel pump

The Porsche Cayenne is a direct-injection engine that uses a high-pressure fuel pump in addition to the regular fuel pump. This high-pressure pump is located on the engine, while the regular fuel pump is located inside the fuel tank.

The high-pressure fuel pump in the Porsche Cayenne's direct injection engine is driven by the left side camshaft and generates between 580 psi or 40 bar and 1740 psi or 120 bar of pressure, depending on whether the engine is idling or at wide-open throttle.

The high-pressure pump is responsible for delivering fuel at a much higher pressure than the regular fuel pump, which typically pressurises fuel to around 40-60 psi or 3-4 bar in older port and throttle-body injection systems.

Replacing the high-pressure fuel pump in a Porsche Cayenne can be a challenging task due to its location at the back of the engine on the driver's side, requiring careful manoeuvring and a significant amount of space to work with.

It is important to note that the high-pressure fuel pump is specific to modern direct-injection engines, which operate at much higher pressures than older carbureted engines. Direct-injection engines utilise two fuel pumps: a regular fuel pump located in the fuel tank and a high-pressure fuel pump mounted on the engine.

The pump is mounted to and driven by the left side cam

The high-pressure fuel pump in the direct injection motors in the Porsche Cayenne is in addition to the regular fuel pump. This pump is mounted to and driven by the left side cam. The left side cam drives the pump, and once the engine is off, it dissipates pressure quickly. However, there will still be some residual fuel in the pump, so it is important to be prepared to catch and dispose of it properly.

When working around fuel, always take the necessary precautions. Wear gloves and eye protection, work in a well-ventilated area, and ensure there are no open flames or hot lights nearby. It is also crucial to let the motor cool down before beginning any work.

Removing the intake manifold is recommended to provide more space to work with. It is challenging to access the pump with the manifold still in place.

To replace the high-pressure fuel pump, follow these steps:

• Remove the belly pans/plastic under trays so that any dropped tools fall to the floor instead of becoming trapped in the pan.
• Remove the plastic coil pack cover (4 torx bolts).
• Remove the plastic piece on the driver's side of the engine bay (3 pop fasteners).
• Allow the engine to cool down completely.
• Cut power to the fuel pumps to prevent them from accidentally turning on.
• Depressurise the fuel system by removing the fuel pump control unit fuse in the engine bay fuse box (number 13 fuse).
• Loosen the low-pressure fuel line from the pump (requires an 18 and 19mm wrench).
• Remove the crash panel by loosening the three bolts with a 10mm wrench.
• Remove the high-pressure line that goes from the pump to the fuel rail with a 17mm wrench.
• Remove the bolts that hold the pump to the engine (2 hexagon head union nuts and 1 mounting bolt, all requiring a 10mm socket).
• Loosen the wiring harness over the back of the valve cover by unclipping the sensor wiring from the sensor and removing the bolts holding the engine hoist hook.
• Remove the pump by gently prying it away from the engine block with a flat-head screwdriver. Rotate the pump to remove the wiring plug from the pump solenoid.
• Pay attention to the metal coupling (Oldham coupling) between the fuel pump and the camshaft. It may fall out during the removal process, so ensure it is accounted for.
• Prepare the new pump by attaching the low-pressure fuel hose, ensuring the correct orientation (torque to 26 foot pounds).
• Reinstall the pump, ensuring the correct orientation of the Oldham coupling.
• Reassemble in the reverse order, clearing any codes using a Durametric tool if necessary.
• Inspect for fuel leaks, and keep a fire extinguisher nearby.

The pump generates between 580 psi and 1740 psi

The high-pressure fuel pump in the direct injection motors in the Porsche Cayenne is in addition to the regular fuel pump. This pump is mounted to and driven by the left-side cam. The pump generates between 580 psi or 40 bar and 1740 psi or 120 bar depending on whether the motor is at idle or wide open throttle.

The left-side cam drives the pump. Once the engine is off, it dissipates pressure quickly. However, even when the engine is cold, there will be some residual fuel in the pump.

When working around fuel, take all necessary precautions. Wear gloves and eye protection, work in a well-ventilated area, and do not work around any open flame or hot lights. Let the motor cool down before beginning work.

The left side cam drives the pump

The high-pressure fuel pump in the direct injection motors in the Porsche Cayenne is in addition to the regular fuel pump. This pump is mounted to and driven by the left side cam. It generates between 580 psi or 40 bar and 1740 psi or 120 bar depending on whether the motor is at idle or wide-open throttle.

The pump sits on the rear of the left head and is driven by the camshaft. A stainless steel line runs out from it to the fuel rail. To access the pump, you will need to remove the intake manifold.

To remove the pump, first, remove the bolts from the protective crash plate behind the pump. Then, disconnect the fuel input and output lines from the pump. Next, remove the bolts that hold the pump to the head. Finally, separate the electrical connection for the pump. When installing a new pump, make sure to line up the pump drive adaptor with the camshaft.

When the engine is off, the pump quickly dissipates pressure

The high-pressure fuel pump in the Porsche Cayenne is in addition to the regular fuel pump. This pump is mounted to and driven by the left-side camshaft and generates between 580 psi or 40 bar and 1740 psi or 120 bar, depending on whether the motor is at idle or wide-open throttle. When the engine is turned off, the pump quickly dissipates pressure.

The left-side camshaft drives the pump. When the engine is off, the pump quickly releases pressure, but there will still be some residual fuel in it. It is important to be prepared to catch this and dispose of it correctly.

When working around fuel, it is important to take the necessary precautions. This includes wearing gloves and eye protection, working in a well-ventilated area, and ensuring there are no open flames or hot lights nearby. It is also recommended to let the motor cool down before beginning any work.

The high-pressure fuel pump is located on the rear of the left head and is driven by the camshaft. There is a stainless steel line running from the pump to the fuel rail. To access the pump, it is necessary to remove the intake manifold, as there is very little space to work with otherwise.

• Remove the intake manifold to access the pump.
• Disconnect the fuel input line from the pump. This is done using a 17mm wrench. Some fuel will spill out, so be prepared to catch it and dispose of it correctly.
• Disconnect the fuel output line from the pump using a 14mm flared nut wrench. Again, some fuel will spill, so be ready to catch it.
• Remove the three bolts that hold the protection plate in place. These bolts also secure the pump to the head.
• Remove the pump from the camshaft. Be careful not to rotate the metal studs that come out of the pump's drive adaptor or let them fall off the end of the shaft, as they need to line up with the camshaft when installing the new pump.
• Separate the electrical connection for the pump. This is easier to do once the pump is off the camshaft.
• Transfer the adaptor plate from the old pump to the new one and rotate the pump until the adaptor plate is in the same direction as the old pump. This will help line up the new pump with the camshaft during installation.

It is important to note that there is a metal coupling, called an Oldham coupling, between the fuel pump and the camshaft. This coupling may fall out during the removal process, so be sure to account for it and put it back in place during the installation of the new pump.

Frequently asked questions