Replacing The Fuel Pump In A 2004 Porsche Cayenne

If you're looking to change the fuel pump on your 2004 Porsche Cayenne, it's worth noting that the fuel pumps on the Porsche Cayenne are often considered to be items that are not a question of if they will fail, but when. It is generally recommended to change both fuel pumps at the same time, as there have been many cases where someone replaced one side, only to have the remaining pump fail shortly after.

The fuel pump is located inside the fuel tank, and to access it, you will need to remove the rear seat bottom to access the fuel pump access plates. The fuel tank is a saddle tank, meaning it has two sides, and there is one fuel pump on each side. The procedure to replace the fuel pumps is as follows:

1. Remove the rear seat bottom to access the fuel pump access plates.

2. Disconnect the battery and have a fire extinguisher nearby.

3. Have the fuel level in the car as low as possible before starting this job. Wait until the car's fuel level is on reserve before opening up the fuel tank.

4. Relieve the pressure in the fuel system prior to removing the fuel lines. Failure to do so can result in pressurized fuel shooting out of the lines when they are disconnected.

5. Remove the access covers using a large screwdriver.

6. Remove the electrical connections and fuel line connections from the fuel pumps.

7. Loosen and remove the retaining rings that hold the fuel pumps in the fuel tank.

8. Carefully pull the fuel pumps up and out of the fuel tank. Be prepared for some fuel to spill out.

9. Install the new fuel pumps, making sure they are seated correctly in the retaining rings.

10. Reattach the electrical and fuel line connections to the new fuel pumps.

11. Reinstall the access covers and rear seat bottom.

Disconnecting the battery

Step 1: Locate the Battery

The battery is located under the driver's side carpet, near the seat. You will need to pull up the carpet to access it. Look for a slit in the carpet and pull it up to reveal the 13mm acorn nut holding the ground lead to the frame.

Step 2: Disconnect the Battery

Once you have located the battery, follow these steps to disconnect it properly:

• Remove the 13mm acorn nut that secures the ground lead to the frame.
• Carefully pull the lead up and off the post.
• Wrap the end of the cable with tape to prevent it from making contact with any bare metal. This is an important safety precaution.

Step 3: Prepare for Fuel Pump Replacement

With the battery disconnected, you can now proceed with the fuel pump replacement. It is important to have a fire extinguisher nearby and ensure that there are no open flames or sources of ignition nearby. Open all doors and the rear hatch to ventilate the work area as fuel vapors can be dangerous. It is also recommended to wear fuel-resistant gloves and a carbon filter mask for protection.

Step 4: Relieve Pressure in the Fuel System

Before removing the fuel lines, it is crucial to relieve the pressure in the fuel system. Failure to do so can result in pressurized fuel spraying out when the lines are disconnected. Relieve the pressure by removing the fuses for the fuel pumps and running the car until it dies.

Step 5: Access the Fuel Pumps

The fuel pumps on the Porsche Cayenne are accessed through a panel underneath the rear seats that leads into the fuel tank. You will need to remove the rear seat cushions and fold the seats up towards the front of the car. Underneath the seats, you will find the fuel tank access panel.

Step 6: Remove the Fuel Tank Access Panel

To remove the access panel, you will need to remove the nuts or bolts holding it in place. There may be multiple bolts or nuts, so make sure to count them and note their locations for proper reassembly. Place plastic sheeting or a drop cloth underneath the car to catch any spilled fuel during the pump replacement.

Step 7: Disconnect the Fuel Lines

With the access panel removed, you will now be able to access the fuel lines and electrical connections to the fuel pumps. Carefully disconnect the fuel lines and electrical connectors. It is important to do this slowly and carefully to avoid any spills or damage to the connectors.

Step 8: Remove and Replace the Fuel Pumps

With the fuel lines and electrical connections disconnected, you can now remove the old fuel pumps. Lift them out of the fuel tank and set them aside. Install the new fuel pumps in the same relative position and secure them in place. Reattach the fuel lines and electrical connectors, making sure all connections are secure and tight.

Step 9: Reassemble and Test

Reinstall the fuel tank access panel, rear seats, and battery. Reconnect the battery, making sure the ground lead is securely attached to the frame. Start the car and check for any leaks or issues. If everything looks good, you have successfully replaced the fuel pump on your 2004 Porsche Cayenne!

Removing the rear seats

To remove the rear seats of a 2004 Porsche Cayenne, you will need to:

• Pull the straps at the front of each rear seat to pull the lower seat cushions up off the floor.
• Once detached from the floor, fold the seats up towards the front of the car.
• Loosen and remove the three 10mm bolts holding the right seat belt bracket to the floor.
• Remove the bracket and clean off any debris.
• Loosen and remove the four 10mm bolts holding the left seat belt bracket to the floor.
• Fold the seat belt buckles forward in order to reach the bolts behind.
• Fold the entire bracket upward.
• Cut the carpet along the perforation in a circle on both sides using a razor blade.
• Fold the carpet back and remove the four 10mm nuts holding the access panel to the floor.
• Pry the access covers off using a large screwdriver.

Locating the fuel pumps

On the driver's side, you will find a slit in the carpet near the seat. Pull up the carpet to expose the 13mm acorn nut holding the ground lead to the frame. Remove this nut and pull up the lead, wrapping the end with tape to prevent contact with any bare metal.

Next, use the pull straps at the front of each rear seat to detach the lower seat cushions and fold the seats towards the front of the car. Directly underneath the seats is the area through which you can access the fuel tank.

Now, you need to remove the seat belt brackets on both sides of the car. For the right-side bracket, loosen and remove the three 10mm bolts holding it in place. Keep in mind that these bolts are usually very tight due to the thread locker compound applied at the factory, so you may need a breaker bar to loosen them. Porsche also recommends replacing these bolts whenever they are removed. Once the bolts are removed, clean off any accumulated debris and set them aside.

For the left-side bracket, remove the four 10mm bolts holding it to the floor. You will need to fold the seatbelt buckles forward to access the bolts. After removing the bolts, fold the bracket upward.

With the brackets removed, you will see that the carpet is perforated in a circular shape on both sides. Cut the carpet along the perforation using a razor blade. Fold back the carpet and remove the four 10mm nuts holding the access panel to the floor. Use a large screwdriver to pry off the access covers.

Underneath the access panel, you will find the fuel pressure regulator (FPR) and the fuel filter. The FPR maintains the fuel pressure level in the system, and it is located on the right side of the car. To remove it, disconnect the fuel line and electrical connections.

On the left side of the car, you will find the fuel filter. Disconnect the electrical connector by pushing the tab and pulling it off. Also, press the tab on the fuel line connector and remove it.

With the FPR and fuel filter disconnected, you can now access the fuel pumps, which are located inside the fuel tank.

Replacing the fuel pumps

The fuel pumps on the Porsche Cayenne are one of those items that are in the "not if, but when it fails" category. As a general rule, it is recommended to change both fuel pumps at the same time. The design of the fuel tank in the Cayenne allows you to not only replace the fuel pumps but also the fuel filter and the fuel pressure regulator if needed.

Safety first

Keep in mind that you will be working around raw fuel. Have a fire extinguisher nearby and obviously keep any flames or sources of ignition well away from the car. Additionally, open all the doors and the rear hatch and make sure the area in which you work is well-ventilated. Fuel vapors can be very dangerous. It is also recommended to wear fuel-resistant gloves and a carbon filter mask to protect yourself.

You'll want to have the fuel level in the car as low as possible before starting this job. Wait until the car's fuel level is on reserve before opening up the fuel tank. If the fuel pump is completely dead, you'll want to use a small pump and hose to get as much fuel out as you can once the fuel filter and fuel pressure regulator are removed. The fuel pump housings themselves can hold quite a bit of fuel. As you pull them up out of the fuel tank, it can be difficult to prevent spilling fuel everywhere. Subsequently, it's a good idea to have plastic sheeting on hand to cover the carpeting.

You'll also need to relieve the pressure in the fuel system prior to removing the fuel lines. Failure to do so can result in pressurized fuel shooting out of the lines when they are disconnected. Relieving the fuel pressure is done by removing the fuses for the fuel pumps and running the car until it dies.

Disconnect the battery

Disconnect the battery and make sure you have a fire extinguisher nearby. The disconnect point is located under the driver's side carpet, near the seat. You'll see a slit in the carpet, pull it up and you'll see the 13mm acorn nut holding the ground lead to the frame. Remove the nut and pull the lead up off the post. Wrap the end of the cable with some tape to prevent it from making contact with any bare metal.

Accessing the fuel pumps

The fuel pumps, fuel filter and fuel pressure regulator on the Porsche Cayenne are accessed through a panel underneath the rear seats that leads into the fuel tank. Use the pull straps at the front of each rear seat to pull the lower seat cushions up off the floor. Once detached from the floor, fold the seats up towards the front of the car.

Removing the seat belt brackets

Loosen and remove the three 10mm bolts holding the right seat belt bracket to the floor. These are also sometimes referred to as triple-square bolts. Do not try to use anything other than the correct tool to remove these. You'll likely strip them out and be in for an even harder job. Keep in mind that these bolts are usually very tight due to the thread locker compound applied at the factory. You'll likely need a breaker bar to get them loose. Porsche also notes that these bolts must be replaced whenever removed. When re-installing the bolts, torque them to 20 Nm (15 ft/lbs). Once the bolts are removed, remove the bracket and clean off any accumulated dog hair or crumbs.

Now remove the four 10mm bolts holding the left seat belt bracket to the floor of the car. You'll need to fold the seat belt buckles forward in order to reach the bolts behind. Once all the bolts are removed, fold the entire bracket upward.

Removing the carpet

On the floor, you'll find that the carpet is perforated in the shape of a circle on both sides. You'll need to cut the carpet with a razor blade along the perforation. Once the carpet has been cut, fold it back and remove the four 10mm nuts holding the access panel to the floor. You'll need to pry the access covers off using a large screwdriver.

Removing the fuel pressure regulator

On the right side of the car, you'll see the fuel pressure regulator. Remove the fuel line connections by pressing in on the tab and pulling the connector off. The electrical connection is removed by pressing in on the tab and pulling the connector off.

Removing the fuel filter

On the left side of the car, you'll find the fuel filter. Remove the electrical connector by pushing the tab in and pulling it off. Press the tab on the fuel line connector and pull it off.

Removing the retaining rings

You will now need to loosen and remove the retaining rings that hold both the fuel pressure regulator and the fuel filter in the fuel tank. Porsche calls for a special tool to do this, although you can loosen the ring by placing a brass tool on the edge of the ring and using a hammer to tap it loose counter-clockwise (do not use a regular screwdriver as this may cause sparks which could ignite the fuel vapors). When re-installing the rings, use a screwdriver to tap the ring clockwise as tight as you can.

Removing the fuel line connectors

Removing the fuel filter

Now carefully pull the fuel filter up and out of the fuel tank. Carefully move the hose connections out of the way as you do. Begin by pulling the fuel filter up enough to pull the electrical connections off the side. You will now have enough room to slide your hands in underneath and feel for the release tabs on the fuel line connectors at the bottom. Pull the fuel lines off and carefully lift the fuel filter out and set it to the side, as one of the hoses is still connected to the fuel pressure regulator on the other side. Be prepared for some gasoline to spill out of the filter.

Removing the fuel pressure regulator

The fuel pressure regulator allows much more access to the connections underneath. In this picture, you can see the two electrical connections that plug into the bottom. Don't worry about reattaching the plugs incorrectly as they only fit on one way.

Once the electrical connections are unplugged, pull the fuel pressure regulator up enough to access the fuel line connections. Squeeze the tabs on the connections and pull the lines off.

Refitting the rear seats

To refit the rear seats, perform the following steps in reverse order:

• Torque the bolts to 20 Nm (15 ft/lbs) and then re-install the seat belt bracket.
• Re-attach the bracket and clean off any accumulated dog hair or crumbs.
• Re-install the four 10mm XZN bolts holding the left seat belt bracket to the floor of the car.
• Re-install the three 10mm XZN bolts holding the right seat belt bracket to the floor.
• Fold the seats up towards the front of the car.
• Pull the lower seat cushions up off the floor using the pull straps at the front of each rear seat.

Frequently asked questions