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Pelican Technical Article:

Fuel Filter Removal

Kerry Jonsson

Time:

2 hours2 hrs

Tab:

$100

Talent:

**

Tools:

17mm, 19mm wrench, Phillips head screwdriver, drain pan for gasoline

Applicable Models:

Mercedes-Benz R129 (1990-02)

Parts Required:

Fuel filter, cooper sealing washers

Hot Tip:

Run engine with fuel pump fuse removed to reduce pressure in the fuel system

Performance Gain:

Restore power due to low fuel pressure and volume

In order for a fuel injected engine to perform its best it needs a more than adequate supply of fuel. Mercedes Benz uses two externally mounted fuel pumps to supply the necessary fuel pressure and volume to the fuel injection system. The fuel pressure is first run through a fuel filter and then on to the fuel injection system. This fuel filter catches impurities, dirt, rust and debris that may have been pumped into your tank during refueling. In this tech article we will go over all the steps to replace your fuel filter cleanly and safely.

Mercedes Benz recommends you replace your fuel filter every 2 years or 30,000 miles, whichever comes first.

In order to service your fuel filter you need to lift up and support the rear axle of your vehicle. See our tech article on jacking up and supporting your vehicle. Also when working with gasoline never have a potential ignition source (drop light) around and have a fire extinguisher around just in case.

Locate your fuel filter (green arrow) under the rear of the car just to the right side of where the driveshaft meets the differential.
Figure 1

Locate your fuel filter (green arrow) under the rear of the car just to the right side of where the driveshaft meets the differential.

Remove the 17mm fitting that is at the back end of the fuel filter.
Figure 2

Remove the 17mm fitting that is at the back end of the fuel filter. You will probably have to put a 19mm wrench on the filter. They provide a hex head on the filter so you can hold it still with a wrench while loosening lines. Have a drain pan ready to catch the fuel that is going to leak out. Never have an ignition source like a drop light when opening fuel lines. After the line is loose allow time for the fuel to drain so it does not drip on you.

While you still have the 19mm wrench on the back end of the fuel filter (green arrow), loosen the 17mm banjo bolt (yellow arrow) at the front of the fuel filter.
Figure 3

While you still have the 19mm wrench on the back end of the fuel filter (green arrow), loosen the 17mm banjo bolt (yellow arrow) at the front of the fuel filter.

Thread out the banjo bolt by hand.
Figure 4

Thread out the banjo bolt by hand. and discard the copper washer (green arrow). You will have to replace the copper sealing washers.

ThisPicture illustrates the fuel filter assembly looking up underneath it.
Figure 5

ThisPicture illustrates the fuel filter assembly looking up underneath it. You do not have to remove it, but only loosen the two Phillips head fasteners (green arrows) that clamp the bracket onto the filter. It is very possible these screws will break when you take them off. Try applying some penetrating oil to the fasteners behind these screws before attempting to remove. Otherwise you may have to drill out broken fasteners.

With the filter loose in the bracket move it toward the back of the car in the direction of the blue arrow.
Figure 6

With the filter loose in the bracket move it toward the back of the car in the direction of the blue arrow. You can use the 19mm wrench on the hex head of the filter to twist is back and forth as you slide it out.

Don't forget on the front of the fuel filter there is another copper sealing washer, you will have to replace the copper sealing washers.
Figure 7

Don't forget on the front of the fuel filter there is another copper sealing washer, you will have to replace the copper sealing washers.

On the rear of the filter there will be an adapter (green arrow).
Figure 8

On the rear of the filter there will be an adapter (green arrow). You will have to remove from the old filter and install on the new one.

Remove the 17mm adapter with a wrench while holding the 19mm hex head on the fuel filter.
Figure 9

Remove the 17mm adapter with a wrench while holding the 19mm hex head on the fuel filter. You can do this with the filter removed but it helps to hold it still while the filter is still in the mounting bracket. Installation is the reverse of the removal steps. Install the adapter in the new filter on the back side of it. Slide the filter into the bracket and tighten down the bracket fasteners. Install the banjo bolt at the front with new crush washers and install the line fitting at the rear of the fuel filter. Turn the key on and crank the car before dropping it off the jack stands and make sure there are no fuel leaks.

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Comments and Suggestions:
Ruindr Comments: I bought the Mahle fuel filter from Pelicanparts. No copper crush washers. Can they be ordered separately?

Also, if you only change the filter, will the tank drain? The connections to the filter is not directly connected to the main hose from the tank strainer.
August 25, 2016
  Followup from the Pelican Staff: Yes, they can. I would suggest clamping the line int he case any excess fuel does drain. - Nick at Pelican Parts  
MJB Comments: Would the fuel filter possibly contribute to flooding of the engine when it warms up or is that more likely the fuel regulator?
May 6, 2016
  Followup from the Pelican Staff: No. More likely the regulator, fuel pump or injector. - Nick at Pelican Parts  
Tired Comments: Do I need to drain the fuel tank?Pulled inlet hose off and have got 10 gallons of fuel so far.Of course the tank was full.Pull the gas cap and it runs like a hose.Hope the gas cap is creating enough vacuum,otherwise drain the whole Frick in tank.There isn't an electric. Solenoid between tank and fuel pump is there.Otherwise gravity rules.Let me know if ya can
April 2, 2016
  Followup from the Pelican Staff: If draining, see if you can clamp off the soft rubber hose to stop flow. Keep a drain pan in place to catch any excess fuel. - Nick at Pelican Parts  
George Comments: Do the copper sealing washer come with the fuel filter with threaded fitting, part number 002 477 44 01 MBZ?
June 4, 2015
  Followup from the Pelican Staff: I recall the sealing washers being in the box.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 

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