DIY: STi fuel pump install

[anothernord]

I am not responsible for anything you do to harm yourself, your car, or anyone else or anything in the world. Fuel vapors are flammable (duh), so DO NOT DO THIS INSTALL IN A CLOSED SPACE! DO IT OUTSIDE IN YOUR DRIVEWAY!


My supercharger project requires that the engine get more fuel. The stock pump could produce the volume and pressure I need, but it would be at the upper limit of its ability. So for about $35 shipped on the Nasioc classifieds, I picked up a 2006 STi fuel pump with harness.


NOTE: This install is identical to a sedan, except you must remove your rear seat in a sedan to access the tank.

Tools Needed:
-Phillips screwdriver
-Needle nose pliers
-8mm socket
-Flat blade screwdriver

Materials:
-Fuel pump w/ harness
-2 inch pipe clamp
-1.5 inch rubber O ring*
-Paper towels or rag

*This can be subistituted for anything, really. You just need something for the pump to rest against that has some give for when you tighten it down.



1. Remove the two clip/popper things from the rear floor panels with a flat blade screwdriver.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3368-1.jpg

2. Remove the four screws holding the cover plate down and take it off. (make sure it is the plate on the RIGHT side of the trunk area as you look in from the tailgate.)

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3369-1.jpg

3. Depressurize the fuel system by unplugging the electrical connector, unscrewing the gas cap, and starting the car. It should die out after a little while. The fuel system should be depressurized.

4. Using a rag, and the pliers, carefully remove the clamps on the hoses, and push them off the metal lines. Fuel will come out, but if it seems it is coming out under pressure, ...you probably didn't depressurize the fuel system. This stage is messy and the reason why you shouldn't do this in a closed space.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3371-1.jpg

5. Using the 8mm socket, unscrew the little bolts holding the sending unit cover to the fuel tank. Using more rags, lift the whole thing out of the fuel tank and place it on the ground. There will be gas everywhere so just let it sit until it evaporates.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3372-1.jpg

5. Unplug the stock fuel pump connector.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3374-1.jpg

6. Remove the hose clamps.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3375-1.jpg

7. Pull the whole pump out and remove the rubber hose section. You will need it to install the new pump.

8. Remove the little black ring from the end of the pump and set it aside. Then remove the filter bag from the old pump.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3376-1.jpg

9. Take the filter bag and push it onto the new pump, then use that small black ring to secure it on your new pump.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3380-1.jpg

10. Slide the rubber hose onto the new pump, and secure it with the old clamps.

11. Plug in the electrical connector.

12. Stick your rubber O ring or whatever you have under the pump, then attach the 2 inch hose clamp. Tighten it in a way that they filter bag pipe is not pushed against the metal bracket.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3385-1.jpg

13. This is what you should have now. Make sure your filter bag is oriented as shown.

https://sl-i.net/FORUM/images/imported/2009/06/IMG_3384-1.jpg

14. Put the whole thing back into the tank, but first stop, double check your assembly, then go ahead.

15. Re-attach the hoses, clamp them down, plug in the connector, and replace a couple bolts to hold the cover in place while you test.

16. Double check everything, replace your gas cap if you didn't already, then put the key into the "on" position. You should hear the pump prime. Start the car and let it run while you check for leakage.

17. If everything works, tighten down the bolts, replace the cover and trim panel, and go clean up since you probably smell like gas.

[Huffer]

Great DIY. Very clear and easy to follow. Nice to know there's no wiring/plug issues either.

[2.5GT]

Very nice.

Did the STi pump noise any louder than stock? and I'm assuming you ran the car with the pump, any difference? we'll without any force induction, it probably won't do much except dump more fuel.

[anothernord]

It purrs just as happily as it ever has. The noise is probably due to the fact that the pump is in contact with the metal bracket, so it transmits the sound more. Its not really much louder, just a little 'whirr' when you turn the key to the "On" position. When driving there is no difference since the fuel pressure regulator controls fuel pressure for a given manifold pressure anyway.

[chuckthefuk]

:grin: another cheap mod. I love lego

im not too sure i understand the benifit of having this..

[chuckthefuk]

im not too sure i understand the benifit of having this..

Besides "renewing" the life of your fuel pump for peanuts. It would allow for more flow if you decide to go with a FPR and bigger injectors. But who builds N/A EJ's anyways :lol:

[anothernord]

I can also confirm the engine now starts a lot faster. It used to take 6 or cranks to start but now it's like 3 or 4 at most. Sometime it starts immediately if it's warm.

[2.5GT]

Ever worry if that little grommet falls out? :lol:

[DLC]

I think that my 180k mile pump is on its way out. Takes a few rotations sometimes, some gas it doesn't like, and recently any acceleration below 2500 RPMs has been met with hesitation, which was sudden.

Awesome writeup.

[anothernord]

Ever worry if that little grommet falls out? :lol:

I thought about that, but it can't really hurt anything, and the pump wouldn't go anywhere otherwise. It would probably start making lots of noise, thereby forcing my to get all covered in gas removing the assembly to fix it.

As a note, this was the third time I took out the whole sending unit. The first time, I dropped a screwdriver into the full tank. :smt012

Luckily, I have a one of those remote grasper claw things. It worked great getting the screwdriver out, but was completely ruined because it will forever reek of gasoline. So when you're working on the unit, put the cover plate over the hole.

Oh and you will lose brain cells from this mod, just plan on it.

[chuckthefuk]

By any chance did this new sending unit fix the wonky gauge readings ?

-Chuck

[Huffer]

One for sale, sans clippy wirey thingy, looks like a motivated seller too.
http://forums.nasioc.com/forums/showthr ... ?t=1794986 (http://forums.nasioc.com/forums/showthread.php?t=1794986)

As for the grommet/O-ring/body spacer - it'd be a relatively simple job to wrap the pump with a bit of rubber and then clamp it, thus removing the concern for a floaty in the tank. I bet if you double strapped it there'd be even less of an issue with it coming loose.

[anothernord]

Oh yeah, I forgot to point out that you must get the wiring harness with whatever pump you decide to upgrade to. The stock pump has 2 eyelet connectors that just attach to open terminals on the back of the stock pump, but the STi pump has an actual socket for its own plug/harness.

[chuckthefuk]

I found a entire sending unit w/ harness for $60 from a 04' STi and I have a few questions:

1) This DIY is for swaping the fuel pump only not the sending unit itself?

2) Could you swap the entire send unit w/ pump

-Chuck

[anothernord]

I found a entire sending unit w/ harness for $60 from a 04' STi and I have a few questions:

1) This DIY is for swaping the fuel pump only not the sending unit itself?

2) Could you swap the entire send unit w/ pump

-Chuck


1. This is just for swapping the fuel pump.

2. Yes, it should just drop in, just check the main electrical connector on the top of the cover to make sure its the same as yours.

[TGX4776]

My supercharger project requires that the engine get more fuel. The stock pump could produce the volume and pressure I need, but it would be at the upper limit of its ability.


I think the fuel pump in my GT went out yesterday and there is an STI fuel pump up for sale near me.

So if I install it the computer will automatically regulate it to work with my engine?

[anothernord]

Well, the car has a fuel pressure regulator, so it would just deliver the same fuel pressure no matter what the pump, unless it sees that it needs more pressure, in the case of a turbo or supercharger. So yes, it will work just fine.

[TGX4776]

OK, thanks for the help!

[Chausx]

I got my fuel pump from Nasioc for $30 shipped which is a steal of a deal. From what I've been looking around for the stock BD Legacy fuel pumps run at around 50gph(~190lph) at a free flow rate while the '05 STI pump I acquired is running at around 60gph(~227lph) a gain of ~40 lph is not a bad deal mainly for the change it costs to get one compared to a Walbro 255lph fuel pump. I'll be doing this swap into my legacy when I start doing the 3.3 swap.

[httrdd]

Thanks nice diy.