Replacing The Fuel Pump In Your 2007 Mercedes Ml320: Step-By-Step Guide

If you notice jolting when you accelerate your 2007 Mercedes-Benz ML320, it could be a sign of a failing fuel pump. Luckily, replacing the fuel pump yourself is a relatively straightforward process. Here's a step-by-step guide to help you get started:

1. Remove the flaps of the rear seats to access the fuel pump.

2. Remove the rear seat bottom covers by releasing the tabs.

3. Unscrew the rear seats and disconnect the SRS cables.

4. Remove the 40% seat (rear passenger side) from the car.

5. Slide the 60% seat to the location of the 40% seat to access the driver's side.

6. Fold the floor mat on the driver's side corner to reveal a round cap covering the access hole.

7. Remove the seal and lift the cap to expose the fuel pump.

8. Take a picture to document the alignment of the pump connections.

9. Unplug the power cable to the pump.

10. Start the engine and wait for it to run out of fuel and stall.

11. Disconnect the fuel lines, being careful to collect any spilled fuel.

12. Turn the locking ring of the pump counterclockwise and remove it.

13. Lift the fuel pump, tilting and turning as needed. Be cautious of the fuel inside the pump reservoir.

14. Insert the new fuel pump, ensuring the alignment of the fuel lines matches the original.

15. Check that the rubber gasket has a tight fit between the pump and the tank.

16. Put the locking ring over the pump and turn it clockwise for at least one full turn.

17. Snap the fuel lines into place and plug in the power cable.

18. Start the engine and use body sealant to seal the cap.

19. Reinstall the rear seats and connect the SRS cables.

It is important to note that working with fuel can be dangerous, so always take the necessary precautions to avoid the risk of explosion or poisoning by inhaling vapors. It is recommended to have the minimum amount of fuel in the tank during the procedure to minimize spills. Additionally, refer to a trusted repair manual or seek professional assistance if you are unsure about any steps.

Removing rear seats

To remove the rear seats of a 2007 Mercedes ML320, follow these steps:

Firstly, locate and remove the flaps of the rear seats. You can find the access site in the first picture of this guide: [https://www.benzworld.org/threads/diy-fuel-pump-remove-install.1390559/]. Then, remove the rear seat bottom covers. There are no screws, just tabs. Be careful when releasing the tabs as they can easily break. You can refer to the detailed instructions in the PDF guide here: [https://www.benzworld.org/threads/diy-fuel-pump-remove-install.1390559/].

Next, unscrew the rear seats. There are two hex nuts and several torx bolts. Disconnect the SRS cables; there is one cable for each seat. Now, remove the 40% seat (rear passenger side) from the car. The 60% seat is very heavy, so just slide it to the location of the 40% seat so that you can access the driver's side.

Fold the floor mat (driver side corner) and you will see a round cap covering the access hole. This cap is attached to the body by sealant only, so it should come off easily. Once removed, you will see the top of the fuel pump. Take a picture to document the alignment of the pump connections.

At this point, you can start to remove the fuel pump by following the remaining steps in the fuel pump removal guide: [https://www.benzworld.org/threads/diy-fuel-pump-remove-install.1390559/].

Note: There are approximately 18 torx bolts holding the rear seats in place, so have the correct tools ready before beginning this process.

Disconnecting cables and hoses

To disconnect the cables and hoses, start by removing the rear seat flaps and bottom covers. There are no screws, just tabs, and releasing them is the most challenging step. You can easily break the tabs, so be careful.

Next, unscrew the rear seats. There are two hex nuts and several torx bolts. Disconnect the SRS cables—one for each seat.

Now, remove the 40% seat (rear passenger side) from the car. The 60% seat is very heavy, so just slide it to the location of the 40% seat so that you can work on the driver's side.

Fold the floor mat (driver's side corner) and you will see a round cap covering the access hole. This cap is attached to the body by sealant only. Remove the seal and lift the cap.

You will now see the top of the fuel pump. Take a picture to document the alignment of the pump connections.

Unplug the cable, which is the power line to the pump.

Start the engine and wait 5-10 seconds until the engine runs out of fuel and stalls.

Now, disconnect the fuel lines. Push the line and press the tabs on each side with your fingers to remove it. Caution: The fuel line in the center (feeding line) is still pressurized from the fuel filter, which stores almost 1/2 quart of remaining fuel. Collect the fuel into a cup immediately after disconnecting the line. Fuel will come from the line, not the pump. There will be some fuel spill, so place towels around to minimize inhalation of the fuel vapour.

Removing the old fuel pump

To remove the old fuel pump from your 2007 Mercedes ML320, you will need to follow these steps:

Step 1: Remove the rear seats and flaps

Remove the flaps of the rear seats. There are no screws holding the flaps in place, just tabs. Be careful when releasing the tabs as they can easily break. You may refer to the detailed instructions in the PDF provided. Once the flaps are removed, you will need to unscrew the rear seats. There are two hex nuts and several torx bolts. Don't forget to disconnect the SRS cables for each seat.

Step 2: Remove the rear seat bottom covers

Remove the rear seat bottom covers. These are held in place by tabs, so be careful when releasing them. You can refer to the detailed instructions in the PDF for this step as well.

Step 3: Remove the 40% seat and slide the 60% seat

First, remove the 40% seat (rear passenger side) from the car. The 60% seat is very heavy, so you will need to slide it to the location of the 40% seat to access the driver's side.

Step 4: Access the fuel pump

Fold the floor mat on the driver's side corner, and you will see a round cap covering the access hole. This cap is attached to the body by a sealant. Remove the seal and lift the cap. You will now see the top of the fuel pump. Take a picture to document the alignment of the pump connections.

Step 5: Disconnect the power line and fuel lines

Unplug the cable which is the power line to the pump. Then, start the engine and wait 5-10 seconds until the engine runs out of fuel and stalls. Now, you can disconnect the fuel lines. Push the line and press the tabs on each side with your fingers to remove it.

Caution: The fuel line in the center (feeding line) is still pressurized and contains fuel. Collect the fuel into a cup immediately after disconnecting the line to minimize fuel spill and inhalation of fuel vapors.

Step 6: Remove the locking ring and lift the fuel pump

Turn the locking ring of the pump counterclockwise and remove it. Now, lift the fuel pump. It won't come straight up because of the fuel sensor floating arm and secondary intake line (tail-like extension tube). Tilting and turning will be enough to remove it.

Caution: There is still some fuel inside the pump reservoir, so be careful not to tilt the pump more than 45 degrees to avoid fuel spill. Also, be careful not to drop anything inside the tank at this point.

Installing the new fuel pump

To install the new fuel pump, follow these steps:

• Check the alignment of the fuel lines and make sure it is the same as the original.
• Ensure that the rubber gasket has a tight fit between the pump and the tank to prevent leaks when the tank is full.
• Place the locking ring over the pump and mark its initial position with a pen.
• Turn the locking ring clockwise for at least 360 degrees (one full turn). If you have the specific MB tool, use it to tighten the locking ring to the specified 65Nm. Otherwise, ensure that it is tight enough to prevent leaks.
• Snap the fuel lines into place, referring to the picture to confirm the correct placement of the feed line.
• Plug in the power cable.
• Start the engine.
• Use body sealant to seal the cap.
• Reinstall the rear seats and other components in the reverse order of removal. Do not forget to connect the SRS cable. Use Loctite for the seat nuts and bolts (40 Nm).

It is important to note that there is a risk of explosion and poisoning by inhaling fuel vapors during this process. Therefore, it is recommended to have a minimum amount of fuel in the tank during the procedure to minimize the risk of fuel spillage.

Reassembling the car

Once you have successfully installed the new fuel pump, you can begin reassembling your car.

First, carefully lower the 60% seat back into place, ensuring it is secure and stable. Next, reconnect the SRS cables to the seats and install the rear seat bottom covers. Make sure the tabs are securely fastened, as this can be a challenging step. Then, screw the rear seats back into place, ensuring the hex nuts and torx bolts are tight.

Now, you can move on to the fuel pump cap. Apply body sealant to the cap and carefully place it back into the access hole, making sure it is attached securely with sealant.

Finally, reinstall the rear seat flaps and ensure they are properly aligned and secured.

Once you have completed these steps, your 2007 Mercedes ML320 should be fully reassembled, and you can start the engine to test out your newly installed fuel pump. Remember to always exercise caution when working with cars and seek professional assistance if needed.

Frequently asked questions