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Pelican Technical Article:

Fuel Pump Replacement

Steve Vernon

Time:

3 hours3 hrs

Tab:

$220 to $300

Talent:

**

Tools:

8mm socket, large flathead screwdriver, hammer

Applicable Models:

Mercedes-Benz C250 (2012-14)
Mercedes-Benz C300 (2008-14)
Mercedes-Benz C350 (2008-14)

Parts Required:

Fuel pump, fuel pump-sealing O-ring

Hot Tip:

Be careful working around gas

Performance Gain:

Better running engine

Complementary Modification:

Replace fuel filter

A faulty fuel pump can cause poor engine performance and hard starting problems. When they fail completely, you may be left with an engine that doesn't run at all. If you are starting to have problems with your pump or getting a faulty error code for the pump make sure to replace it right away before it leaves you stranded on the side of the road.

There are a host of different fuel pumps for the W204, and all of them are VIN specific. If you are going to replace your pump please make sure to have your VIN handy when ordering because your vehicle will not run with the wrong pump installed. There are also different procedures for the different pumps but this article will cover the pump on our May 2008 C350.

It is best to replace your fuel pump with the fuel tank drained. This reduces the amount of possible spilled fuel and fuel vapors. Wear proper clothing, gloves and safety glasses when working with gas. When replacing, work in a well-ventilated area. Working outdoors is a good choice. Do not use incandescent work lights or power tools and DO NOT smoke. Fuel and fuel vapors are highly combustible.

Begin by opening the fuel filler door and removing the gas cap.
Figure 1

Begin by opening the fuel filler door and removing the gas cap. This will help relieve pressure in the system.

The fuel pump is located under the right side rear seat (red arrow).
Figure 2

The fuel pump is located under the right side rear seat (red arrow). You will need to remove the lower seat to access it. Please see our article on seat removal for further instructions.

With the lower rear seat and under pad removed you will have access to the cover.
Figure 3

With the lower rear seat and under pad removed you will have access to the cover. Remove the four 8mm bolts holding the cover in place (red arrows). Lift the cover up and off, separating the gasket around the wiring harness.

Clean the dust and debris off the top of the pump and unplug the one connection (red arrow).
Figure 4

Clean the dust and debris off the top of the pump and unplug the one connection (red arrow). Separate the other electrical connection. Remove the plug from where it mounts on top of the pump (yellow arrow).

You will need to remove the locking ring that holds the pump in place in the gas tank.
Figure 5

You will need to remove the locking ring that holds the pump in place in the gas tank. While Mercedes makes an expensive tool for doing this, if you are careful you can use a large flathead screwdriver and small hammer and gently tap the ring back off the tabs. Use the holes in the other retaining ring and tap evenly around the entire outside of the ring (red arrows). Do not just start hammering away on one spot. Instead, continuously move around the ring. There should be a witness mark on the ring (yellow arrows) that will let you know when it is fully locked (the one on the photograph is unlocked).

Remove the retaining ring and note the position of the pump in the tank.
Figure 6

Remove the retaining ring and note the position of the pump in the tank. The large tab on the front of the pump lid must face towards the front of the vehicle (red arrow).

Pull the lid of the pump up and off.
Figure 7

Pull the lid of the pump up and off. There is a sealing ring between it and the tank so it might stick a little. There are two prongs with springs on them (red arrows). These sit inside the pump housing and hold it in place. Disconnect the two electrical connections (yellow arrows).

Unclip the open-ended hose from the pump housing (red arrow).
Figure 8

Unclip the open-ended hose from the pump housing (red arrow).

Press in the tab on the other hose fitting and lift it off the pump (red arrow).
Figure 9

Press in the tab on the other hose fitting and lift it off the pump (red arrow).

You can now lift the pump out from the tank.
Figure 10

You can now lift the pump out from the tank. Use care that you do not bend or damage the right side level detector (red arrow). The pump housing will be full of fuel so make sure to carefully pour it back into the tank before taking the pump out of the vehicle. Installation is the reverse of removal. Make sure that the lid is positioned and sealed correctly.

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Comments and Suggestions:
shiva Comments: Hi , can you make a DIY for fuel injecter cleaning with otc tool 7448 or similar tool thanks
October 9, 2016
  Followup from the Pelican Staff: We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.
- Nick at Pelican Parts
 

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