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Registered User
2,210 Posts
Discussion Starter · #1 · (Edited)
Installed a Walbro GSS342 fuel pump into my wagon this evening. Total install time was about one hour, and I found it to be a pretty trivial task. This fuel pump is a direct drop in replacement. I did make a small modification for my own peace of mind, but it was probably unecessary (more on that below).

The procedure I took is as follows:

- Unscrew fuel cap, disconnect green plug behind passenger footwell trim, crank motor for one minute.
- Disconnect battery. If you are doing the install outside, make sure your windows are up first.
- Open all doors.
- Fold rear seats, remove the scrolling trunk cover.
- Remove all the cargo area floor sections piece by piece. Several plastics snaps (only broke one, yay!)
- Remove the donut.
- On the passenger side directly behind the folded seat, there is an ovalized metal cover. Remove it. Remove the foam under it to expose the fuel lines.
- Disconnect the electrical connector.
- Disconnect the feed hose. This is the one with the plastic clip (closest to front of vehicle) and it will still be pressurized with fuel. Use a bunch of shop towels to cover the area, reach underneath the towels and pop off the pressurized hose. A decent amount of fuel will escape under pressure (probably about a cup worth). Hopefully your paper towels caught it all.
- Disconnect the two return/breather hoses. These may dribble a miniscule amount of gasoline.
- Unbolt the fuel tank cover / pump assembly. It is retained by a number of 8mm hex bolts.
- Push the hoses and electrical connector clear of the cover.
- Very carefully lift away the entire assembly. Be careful not to bend anything. At the very last you will likely need to rotate it to get the float and strainer clear of the tank.
- DO NOT drop anything into the tank. You'll be singin' the blues else.
- Have more paper towel on hand on which to catch the drips from the pump assembly.
- Cover the opening with a towel or something to stop excessive fumes from accumulating in your WRX.
- Remove the assembly from the vehicle and take to a clean dry working surface.
- Remove the electrical connector from the pump.
- Displace the clips holding the rubber connecting hose.
- Firmly lift the pump away from its rubber cradle, and then pull free from the hose. The pump is simply held in place by the rubber hose pushing it into the cradle.
- Remove the strainer from the oe pump and fit it to the new pump.
- Fit up the GSS342 into the cradle. At this point you will notice two things:
- 1. The electrical connector is a direct fit.
- 2. Because the Walbro pump is slightly longer than oe, the pump output line pushes against the metal line that it is to be connected to with the rubber hose. If this bothers you (it did me), trim about a 1/4 - 1/2" from the metal line. If you do this, definitely use the hose clamps supplied with the Walbro to secure the rubber line. They will provide a more secure fit than the oe clips.

- Reverse the procedure to refit the new pump.


The pump is marginally noisier than stock. I can hear it intermittently at idle, but not at all once the car is moving. When you first turn the ignition key and the pump primes the system (a couple of seconds) it is loud. Sounds cool though!


7,636 Posts
this should go into tutorial.

congrats pace, with the pump and injectors, have you increased boost at all? retuned the EMS?


Registered User
2,210 Posts
Discussion Starter · #3 ·
Well for some reason the EMS went into some kind of limp mode a couple of days ago (before I installed the pump). This was accompanied by a flashing CEL, but no code stored. So, disconnecting the battery for the pump install will bring a very much needed ECU reset.

I will probably bump the boost back up to 1.2 bar that I was originally running before I turned it down to 1.1 a couple of weeks ago. The biggest need right now is for an EBC, since the Unichip/ECU control leaves a lot to be desired.

I will move this thread to the Tutorial forum, good call.

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