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Pelican Technical Article:

Fuel Filter Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$300

Talent:

*****

Tools:

Flathead screwdriver, 8mm socket, fuel pump collar tool

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Fuel filter, fuel pump and filter sealing O-ring, fuel filter and pump collars

Hot Tip:

Clean top of fuel tank before removing pump

Performance Gain:

Restore good fuel flow

Complementary Modification:

Replace fuel pump

In modern Mercedes-Benz automobiles the fuel pump is electric and located inside the saddle-fuel tank. The fuel pump creates positive pressure in the fuel lines, pushing gasoline to the fuel rail, where the DME controls flow to the engine via a programmed fuel injection map. In tank fuel pumps have many benefits. The fuel is submerged in fuel keeping it cool, preventing vapor lock and electrical issues. The fuel pump delivers a constant flow of gasoline to the fuel pressure regulator, located in the left side of the fuel tank. The fuel then flows to the fuel rail at a regulated pressure and volume. The fuel pump draws fuel from the right side of the saddle style fuel tank and pushes it through the fuel filter in the left side of the tank. Unlike many modern cars, the fuel filter in these models is serviceable as a module.

A dirty or restricted fuel filter can cause poor engine performance and hard starting problems. If you suspect this is your issue, you should replace your fuel filter.

Replacing the fuel filter on a W211 can be done without removing the fuel tank. The fuel filter is located in the left side (driver side) of the fuel tank. There is an access panel below the passenger seat cushion. You will have to remove the lines from the fuel pump module as well, and feed them through the tank. You do not have to remove the fuel pump when replacing the filter.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

It is best to replace your fuel filter with the fuel tank drained. This reduces the amount of possible spilled fuel and fuel vapors. When replacing, work in a well ventilated area. Working outdoors is a good choice. Do not use incandescent work lights or power tools. Fuel and fuel vapors are highly combustible.

Drain your fuel tank. Run the vehicle for about 20 seconds. This equalizes the amount of fuel in the siphon unit.

Disconnect the negative battery cable. See our tech article on battery replacing and reconnecting notes.

Remove the fuel cap, then slide an anti-static siphon hose down the fuel filler neck. Once the hose has bottomed out, pump fuel out of the fuel tank into a suitable storage container. If you are unsure of the amount of fuel in your tank, you can monitor the fuel level via the fuel level sender unit. As the fuel level drops, the fuel level sender resistance drops. You can measure this across the terminals at both sender units with a digital volt / ohm meter (DVOM). You will need a wiring diagram from a repair manual.

Start at the left side seat cushion.
Figure 1

Start at the left side seat cushion. In front of the cushion is a small plastic release lever. Pull the lever up to release the seat cushion latch.

Fold the seat cushion forward.
Figure 2

Fold the seat cushion forward. The left side is shown. Repeat the steps for the right side.

With the seat cushion folded forward, remove the carpet from below the seat.
Figure 3

With the seat cushion folded forward, remove the carpet from below the seat. Pull it up at the corner to detach the clip (red arrow). Pull the carpet out from under the plastic trim. The left side is shown. Repeat the steps for the right side.

Peel the carpet away from the body and support out of your way.
Figure 4

Peel the carpet away from the body and support out of your way. I have mine propped up with a steering wheel holder (red arrow). Even though the fuel filter is located in the left side of the fuel tank (green arrow), you will have to remove the fuel pump access cover to detach the lines and electrical harness.

Starting at the left side.
Figure 5

Starting at the left side. Remove the six 8mm access cover fasteners (red arrows). Then lever the access cover up and remove it (inset).

Disconnect the fuel pump electrical connector by pressing the release tab and pulling the connector straight off to remove it.
Figure 6

Disconnect the fuel pump electrical connector by pressing the release tab and pulling the connector straight off to remove it.

Move to the right side.
Figure 7

Move to the right side. Remove the six 8mm access cover fasteners (red arrows). Then lever the access cover up and remove it (inset).

Next, you have to unscrew fuel pump module threaded collar (red arrow).
Figure 8

Next, you have to unscrew fuel pump module threaded collar (red arrow). There is a special tool made to do this. The tool has notches that match the teeth on the collar. Loosen and remove the collar.

However, if you do not have this tool you can use a brass punch and a rubber mallet.
Figure 9

However, if you do not have this tool you can use a brass punch and a rubber mallet. Using the brash punch and a rubber mallet, tap the threaded collar on one of the ridges counter-clockwise to loosen. Once loose, unscrew the remainder of the way by hand. If the collar is damaged during this process, you will need to replace it with a new part.

Remove the collar from the fuel tank and store it in a safe place.
Figure 10

Remove the collar from the fuel tank and store it in a safe place. Gently lever the top of the fuel pump module up to free it from the tank seal (green arrow).

Slowly lift the fuel pump module top up and remove it.
Figure 11

Slowly lift the fuel pump module top up and remove it. Then pull the seal out of the fuel tank (green arrow).

Next, you have to remove the lines and electrical connectors at the fuel pump module.
Figure 12

Next, you have to remove the lines and electrical connectors at the fuel pump module. Press the release tab (red arrow) and pull the electrical connector straight out to remove it. Then, press the release tab (green arrows) in toward the line and hold. Then slide the line off the fuel pump module.

Next, you have to remove the lines to the fuel pump housing.
Figure 13

Next, you have to remove the lines to the fuel pump housing. Pull both lines (red arrows) straight out of the holders and lay them aside. Once all the lines and the electrical connectors are removed, attach a 10-foot piece of mechanics wire to them all. When you remove the fuel filter, these lines remain attached to it. You will pull the wire through the tank. Then attach it to the new fuel filter assembly to help feed the lines back to the fuel pump.

Back to the left side of the fuel tank, remove the fuel tank pressure sensor electrical connector.
Figure 14

Back to the left side of the fuel tank, remove the fuel tank pressure sensor electrical connector. Release the clip (red arrow) by pulling it up and remove the connector. Then loosen the hose clamp (yellow arrow) and remove the fuel line from the fuel filter.

When removing the fuel line, wrap the line with a rag to prevent fuel spillage.
Figure 15

When removing the fuel line, wrap the line with a rag to prevent fuel spillage.

Remove the collar (red arrow) from the fuel tank and store it in a safe place.
Figure 16

Remove the collar (red arrow) from the fuel tank and store it in a safe place.

Gently lever the top of the fuel pump module up to free it from the tank seal (red arrow).
Figure 17

Gently lever the top of the fuel pump module up to free it from the tank seal (red arrow).

Slowly lift the fuel filter up slightly out of the tank with the seal (red arrow).
Figure 18

Slowly lift the fuel filter up slightly out of the tank with the seal (red arrow). Be sure to guide the bottom of the unit and level sender (green arrow) out of the fuel tank safely. Then feed the lines and wiring harness out along with the end of the mechanics wire. Be sure that the mechanics wire is still sticking out the right side of the tank to aid in reinstalling the lines.

Slide the new fuel filter assembly into the fuel tank.
Figure 19

Slide the new fuel filter assembly into the fuel tank. Attach the mechanics wire to the new lines. Then pull the lines through to the right side of the tank as you feed the filter assembly into the fuel tank. Reattach the fuel lines and electrical connector to the fuel pump module. Hand-tighten the threaded collars. Then tap the collars tight (clockwise) with a brass punch and a rubber mallet. Fill the fuel tank with about two gallons of fuel before attempting to start. Once you are sure that the fuel pump is operating normally, fill the remainder of the fuel tank and check for leaks. Once done, reassemble the interior.





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Comments and Suggestions:
julius Comments: Hi i have one 2005 E 200 kompressor w211 body and the engine can not run, what is the most likely what is wrong, fuel pump or filter?
August 29, 2016
  Followup from the Pelican Staff: I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and fuel pressure, volume, quality and engine compression. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
Mike Lynch Comments: you can just change the fuel filter for 20 bucks from febi bilstein plus it easier and faster. I emailed customer service to add my diy
July 11, 2016
  Followup from the Pelican Staff: I wouldn't say it is easier, as the filter housing has to be removed and the paper element adds steps. It is a money saver for sure though. Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Duke Comments: really concerned regarding this issue of fuel filter replacement for my 2004 Mercedes E320. Previous guidelines indicate the fuel filter in located under the right rear fender, vice located inside the left area under the rear seat. Can you verify this information
May 23, 2016
  Followup from the Pelican Staff: Everything I have says it is located where shown in the tech article, for 2004 MY. - Nick at Pelican Parts  

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