Credits:
I Must thank Kosti for posting the initial thread on this upgrade:
http://www.ozliberty.com/home/index.php … mp;id=7610

I have used the above thread as the basis (borrowed a few photos).  I decided to post up a clearer guide as I thought the modifications on the assembly required were not clear enough.

Tools Used:
1 x Phillips Head Screwdriver
1 x Flat Head Screwdriver
1 x Thin Flat Head Screwdriver
1 x 1/4” dr socket set (1/2” will do just don’t use heaps of torque as the threads will strip easily)
1 x Needle nose pliers
1 x Small file set (needs to be max of 3mm wide)
1 x Dremel Tool (handy and makes job quick but not needed)
1 x Bucket
1 x Workshop rags

Parts:
1.    Wallbro GSS342 Fuel Pump (GSS341 does not fit the Liberty Gen3 fuel pump assembly as inlet/outlet need to be on the same side) ~$180


2.    Replacement fuel filter (Subaru Part Number 42072AE000) ~$45


3.    Replacement fuel filter o-ring (Subaru Part Number 42075AE020) ~$5
4.    Replacement fuel filter seal (Subaru Part Number 42075AE030) ~$5


Theory:
1.    As you wind up the boost and need more fuel, then you’ll eventually reach a limit on how much fuel the OEM pump can deliver.  After this limit has been reached the engine will lean out and then start to detonate.  Detonation = BAD (typically new bottom end or engine rebuild)
2.    As the Fuel pump assembly also contains the only fuel fitler, you might as well change that whilst you’re there.

Time Needed:
1 hour

Method
1.    Start with a low level in fuel tank (less chance of spilling fuel everywhere)
2.    Park car on flat surface
3.    Leave car standing over night so as to depressureise fuel system
4.    Disconnect Battery ground
5.    Fold the RHS rear seat forward.
6.    Fold the vinyl cover that you see forward (you can unplug the clips, but it’s not necessary).
7.    Remove screws that hold on cover
8.    Remove cover



Note: Don’t twist the connectors listed below as they easily snap off (I know from experience)
Note: Have rags ready to catch excess fuel

9.    Remove Electrical Connector
10.    Using needle nose pliers remove:
   a.    Breather line (clamp)
   b.    Return line (clip)
   c.    Out line (Large Clip)

11.    Remove bolts that hold in fuel pump assembly.
12.    Remove fuel pump assembly by rotating counter-clockwise so as to not catch the float assembly on the cover.




Change Fuel Filter whilst we’re here
13.    Screw off large brass looking cover to access fuel filter
14.    Change fuel filter and o-ring.

15.    Re-attach Fuel Filter assembly

Removing the pump
16.    Using Flat head screwdriver pry open clip that retains base of fuel pump assembly
17.    Remove the cover and base rubbers from the pump.  OEM rubber is used in re-install.
18.    Using small flat head screw driver remove fuel sock from base of pump (don’t lose the washer)

Note: Wallbro Unit is ~4mm longer than OEM unit.  We need to make an additional 4mm length in the housing so the Wallbro unit will fit.


Now we start on modifying assembly for new pump
19.    Remove the flat parts of the tab on the main assembly with a small file (or dremel.
before:


after:


20.    Extend the mating slot on the pump base downwards by 2mm with a small file (or dremel).
Before:

After:

21.    Remove the raised rings adjacent the pump outlet with a small file (or dremel).
Before:


After:


Now to start re-assembly
22.    Attach the OEM filter sock to the Wallbro GSS342.
23.    Remainder of assembly is reverse of disassembly.

Note: The OEM fuel sock will ever so slightly contact the bottom of the fuel pump.  This is nothing to worry about.
Note: The Wallbro GSS342 is a slightly noisier pump than the OEM unit, this cannot be heard above the stereo or though unless you’re listening for it.

Cheers
Darryl