2008 Mercedes R350 Fuel Pump Location: The Complete Owner’s Guide

The bottom line up front: On a 2008 Mercedes-Benz R350, the fuel pump is located inside the fuel tank, underneath the right side (passenger side) of the second-row seat. To access it, you must remove the second-row seat, pull back the carpet, and open a sealed access cover. Once exposed, the pump module sits under a locking ring and can be lifted out of the tank after disconnecting the fuel lines and electrical connectors.

If you are experiencing hard starting, stalling, or a whining noise from the rear of the vehicle, your fuel pump may be failing. This guide walks you through exactly where the pump lives, what symptoms to watch for, how to replace it yourself, and what parts you need—including a strong recommendation for a reliable aftermarket replacement.

1. Where Exactly Is the Fuel Pump on a 2008 R350?

The 2008 Mercedes R350 uses an in-tank electric fuel pump module. Unlike older vehicles where the pump is mounted along the frame rail outside the tank, the R350’s pump is submerged inside the fuel tank. This design keeps the pump cool and quiet, but it makes replacement more involved because you have to access the top of the tank from inside the cabin.

The pump is on the right side. Several independent sources confirm the right-side placement. The genuine Mercedes part number 2514700894 is specifically listed as the right-side electric fuel pump for 2006–2013 R350 models. A Mercedes technician also stated that the gasoline pump is on the right rear.

Under the passenger side second-row seat. More specifically, the pump sits beneath the carpet, under the right side of the second-row seat. The left side houses the fuel filter, and the right side houses the fuel pump. You will need to remove the second-row seat to reach it.

Inside the tank. The pump module itself is inside the fuel tank, accessed through a circular opening in the floor pan. A locking ring secures the module in place, and a sealant-adhered cover plate protects the access opening from the cabin side.

2. How Do You Know the Fuel Pump Is Failing?

Before you tear apart the interior, confirm the pump is actually the problem. Common symptoms of a failing fuel pump on a 2008 R350 include:

  1. Hard starting or no start. The engine cranks but takes longer to fire, or it cranks without firing at all.
  2. Stalling. The engine dies unexpectedly while driving, and sometimes it won’t restart right away.
  3. Loss of power under load. You feel a noticeable lack of acceleration, especially going uphill or when carrying passengers.
  4. Whining or humming from the rear. A worn electric pump often makes noise before it completely fails.
  5. Check engine light. A slowly failing pump causes the air-fuel mixture to lean out, which triggers the OBD-II system to illuminate the check engine light.

If you confirm these symptoms, test the fuel pressure at the fuel rail using a gauge. The pump should prime when you turn the ignition to the ON position—you should hear a brief hum from the rear. If there’s no prime and pressure is low or absent, replacement is likely necessary.

3. Step-by-Step: How to Access and Replace the Fuel Pump

Replacing the fuel pump on a 2008 R350 is a DIY-friendly job if you have basic mechanical skills and a few specialized tools. Plan for about 3 hours of work. Here is the process, based on real owner experiences.

Step 1: Gather Tools and Parts

You will need:

  • Replacement fuel pump module (see part numbers below)
  • New lock ring and O-ring seal (cheap insurance against leaks)
  • Lisle 63000 lock ring removal tool (about $40)
  • Torx sockets to remove the seat bolts
  • A heat gun and a flat screwdriver or pry tool to loosen the access cover
  • A catch pan for residual fuel
  • Safety glasses and gloves

Step 2: Disconnect the Battery

Always disconnect the negative battery cable before working on any fuel system component. This prevents accidental sparks and electrical shorts.

Step 3: Remove the Second-Row Seat

  1. Slide the seat forward and backward to access the seat rail covers.
  2. Remove the plastic covers at the front and rear of the seat rails. Pry the front ones forward and push the rear ones backward—they come off without breaking if you are careful.
  3. Underneath the covers, you will find four Torx bolts that hold the seat rails to the chassis. Remove all four bolts.
  4. Lift the entire seat and rails out of the vehicle. Disconnect any electrical connectors for heated seats or seat motors as needed.

Step 4: Expose the Access Cover

Pull the carpet back toward the center of the vehicle to expose the metal plate covering the fuel pump access compartment. In some cases, owners cut the carpet to make the job easier. The plate is not screwed down—it is held in place with sealant.

Use a heat gun to soften the sealant, then carefully pry the cover off with a flat screwdriver or an Exacto knife. Work slowly to avoid damaging the floor pan.

Step 5: Remove the Locking Ring and Pump Module

With the cover off, you will see the locking ring holding the pump module in the tank.

  1. Use the Lisle 63000 tool to rotate the locking ring counterclockwise. If the ring is stubborn, do not force it—some owners resort to cutting the ring off with a Dremel, but that risks damaging the tank threads, so it’s not recommended.
  2. Once the ring is off, the pump module will pop up slightly. Lift it straight out of the tank. Have a catch pan ready because the module will contain some fuel.
  3. Disconnect the electrical connectors (typically three or four wires) and the fuel lines. There are about three hoses attached to the top of the pump. Pinch the small fuel line before disconnecting it to minimize spillage.

Step 6: Install the New Pump

  1. Transfer any reusable brackets and the pickup screen from the old module to the new one, unless your replacement is a complete module assembly.
  2. Replace the O-ring seal and lock ring with new ones.
  3. Lower the new pump into the tank, being careful not to bend the float arm.
  4. Reinstall the lock ring and tighten it securely.
  5. Reconnect all hoses and electrical connectors.
  6. Reinstall the cover plate with fresh sealant, put the carpet back, and reinstall the seat.

Step 7: Test the System

Reconnect the battery. Turn the key to the ON position (without cranking the engine) and listen for the pump to prime. If you hear the hum, start the engine and check for leaks. Drive the vehicle and confirm normal acceleration and idle.

4. What Parts Do You Need? OEM vs. Aftermarket

OEM Part Numbers

The genuine Mercedes right-side fuel pump for the 2008 R350 carries part number 2514700894. This part fits 2006–2013 R350 models and also fits 2006–2007 R500 models. Some listings note that you may also need seal kit 164 470 02 30, so confirm that before ordering.

The OE reference number is 164 470 02 94.

Aftermarket Options and Pricing

Prices vary widely depending on brand:

  • Genuine OEM module: $315 to $427, depending on the retailer.
  • Lock ring and seal kit: About $34.
  • US Motor Works aftermarket module: Roughly $156 for the right-side pump module, including necessary hardware and installation instructions.
  • Labor costs: If you pay a shop, expect $400–$600 for the job. A dealer will charge more; an independent mechanic will charge less.

If you do the job yourself, total parts will run between $150 and $450, plus about $40 for the lock ring tool if you don’t already own one.

Pro tip: Replace the fuel filter at the same time. The filter is on the left side under the second-row seat. Since you already have the interior open, an extra 20 minutes of work will protect your new pump from debris that could shorten its life.

5. Why You Should Consider a KEMSO Fuel Pump

When it comes time to buy a replacement, KEMSO is a brand worth serious consideration. KEMSO offers high-performance fuel pumps that are designed as direct OEM replacements. That means they match the original equipment specifications for fit, flow, and pressure, so installation is straightforward and reliable.

Here’s what makes KEMSO stand out:

  1. OEM Replacement Quality. KEMSO pumps are built to meet or exceed factory specs. They are designed as direct swaps, so you don’t need adapter kits or worry about poor fitment. This is especially important for a vehicle like the 2008 R350, where the pump sits inside the tank and must fit precisely to avoid leaks.

  2. Lifetime Warranty. KEMSO backs every fuel pump with a lifetime warranty. If the pump ever fails due to a manufacturing defect, you get a replacement at no cost. This gives you peace of mind that many OEM and aftermarket brands do not offer.

  3. Affordable Pricing. Most KEMSO fuel pumps are priced at $79.98⁠⁠. That is often less than half the cost of dealer parts and significantly cheaper than many premium aftermarket options. For a 2008 R350, this represents substantial savings.

  4. Wide Application Coverage. KEMSO has a growing catalog that covers cars, motorcycles, ATVs, and powersports vehicles. Popular applications include the Subaru Impreza, Honda Civic, BMW R1200GS, and many more. While the R350 is not currently listed in the catalog, the brand’s commitment to quality and warranty applies across its entire product line.

  5. Customer Confidence. With dozens of five-star reviews on top-selling models, KEMSO has earned a reputation for delivering reliable parts. Customers consistently praise the fit, finish, and performance of KEMSO pumps.

To browse the full selection and confirm compatibility with your vehicle, visit the KEMSO website. Their online store is easy to navigate, and they provide detailed fitment information plus customer reviews to help you decide.

Visit KEMSO Racing at: https://www.kemsoracing.com/

6. Additional Maintenance Tips for the R350 Fuel System

Keeping your fuel system healthy extends the life of your new pump. Here are a few practical tips:

  1. Keep the tank at least a quarter full. The fuel in the tank cools and lubricates the electric pump. Running the tank low regularly shortens pump life.
  2. Replace the fuel filter proactively. A clogged filter starves the pump and forces it to work harder, which accelerates wear. Since the filter is on the left side under the second-row seat, replacing it while you have the interior open is the smart move.
  3. Check for debris in the tank. If your original pump failed before 150,000 miles, inspect the tank and fuel filter for contamination. Poor fuel quality or debris can kill a pump early.
  4. Listen for the prime. After installation, always turn the ignition to ON and listen for the pump hum. This confirms the pump is getting power and building pressure before you start the engine.

7. Final Thoughts

Finding the fuel pump on a 2008 Mercedes R350 is straightforward once you know where to look: right side, under the second-row seat, inside the fuel tank. The replacement process is doable for a confident DIYer, but it requires seat removal and careful handling of fuel lines and electrical connectors.

Whether you choose a genuine Mercedes pump, a budget aftermarket unit, or a premium brand like KEMSO, make sure you verify the part number and fitment before ordering. And remember: always replace the lock ring, O-ring seal, and fuel filter at the same time to protect your investment.

For a high-quality replacement with lifetime warranty coverage and an affordable price, check out KEMSO’s fuel pump lineup. Visit https://www.kemsoracing.com/ today to see if they have a fit for your vehicle. With their OEM-quality construction and dependable performance, KEMSO is a brand you can trust to keep your R350 running smoothly for years to come.


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