club.liberty.asn.au

Hey gents,
Hope it's not a repeat but at what point will the stock fuel pump and injectors max out? Secondly is there a method to figuring out what size injectors and fuel pump to change to? Recommended sellers?

Asked and answered many times here
IIRC:
Around 200atw is where the headroom starts to run out, and which point some headroom can be brought back by installing an FPR and raising the line pressure. eg here: viewtopic.php?f=10&t=16629

Basically the stockers are good for what a stock ej255 or auto box can handle with some measure of longterm relibility if correctly tuned, supported and maintained. But more headroom is welcome as a supporting mod.

Look for Matts / Kido / Throttlehappy posts on this subject for specifics, they're out there...

ID1000's w/ pnp adapters from PSR or Tuspeed.

ID1300's if E85 / on a built bottom end.

DW65c, DW300 from those vendors too.
Get a new intank filter too.
Some pumps need mods others little or less.

View this profile for stages/mods/power info: viewtopic.php?f=10&t=16629

This is really interesting Ben.
I'm at 195wkw now, and am upgrading to UEL headers, cold air intake, and intercooler. This should push me up to the 210-220 mark if all goes well. I asked my tuner (msr) if I'd need to upgrade the pump and injectors for this and he said no.
So I wonder if the stock stuff can go past 200... I guess I'll find out in a couple of weeks.
I have a friend with an MY12 wrx tuned by msr that is on 229wkw with stock pump and injectors. Do they have different injectors?

Peady I would have thought at that power replacing fuel pump would be good insurance rather than a necessity, and one I would invest in. I intend to make less power than you but given I am due for replacing the filter and I have done 125K I am thinking just replace the pump. I just need to do some research on one.

I totally hear you, but I wasn't looking at pumps on the chance my oem one dies, it was whether or not the stock pump can handle over 200wkw.
But either way, replacing the fuel pump can be done at any time in the future I guess...... dammit I guess I should buy a fuel pump.. more money!! Any recommendations? Do i need the dw300 if I don't want to run E85?

According to MSR the stock pump is good to 230kwatw. That's "fine to use at that power level" not "you'll blow your engine up, because the pump isn't coping anymore". The catch is - michael is careful tuner and knows subarus inside and out.

If you're getting tuned by someone else, not on a dyno, without an afr gauge, tuner hasn't slept all night because he's been tuning 10 other cars non stop etc etc - then yes you'd want a bigger pump and whatever else that helps overshoot your fuel supply needs.

On the note of the auto box, from experience the postfl box can handle much more than what the stock ej255 can handle.

alexeiwoody wrote:According to MSR the stock pump is good to 230kwatw. That's "fine to use at that power level" not "you'll blow your engine up, because the pump isn't coping anymore". The catch is - michael is careful tuner and knows subarus inside and out.

If you're getting tuned by someone else, not on a dyno, without an afr gauge, tuner hasn't slept all night because he's been tuning 10 other cars non stop etc etc - then yes you'd want a bigger pump and whatever else that helps overshoot your fuel supply needs.

On the note of the auto box, from experience the postfl box can handle much more than what the stock ej255 can handle.

Yes surely Cobb who have the data to back it up, EcuTek and ProDrive who have proven the pump can only support 130LpH of fuel flow at 45psi rail pressure... then again I guess when Subaru rated the factory pumps they must not have known the one tuner in the world knows better who uses 63+psi rail pressure. Its interesting having a fuel flow gauge on a Mainline dyno when your dynoing a car with under 10000kms on it, makes you wonder how much flow potential a car has as the pump wears and consistently wears faster on higher rail pressure cause engineers know wear is exponential to RPM.

Regardless, Adam ran P100 for a while and we all saw on Facebook what ethanol does to a fuel filter... how much fuel flow do you think goes through a gunked up filter like that?

Heres an idea, Adam just get your fuel pumps filter replaced which is ideal for optimal fuel flow. When the pump comes out, you can see the filter and get a DW65c fitted at the same time if the pumps corrodes from P100 usage.

Feisty haha
As much as I enjoy seeing Matt and Alexei debate, I'll just get a fuel pump to be safe. DW65c look good as i dont want to have to modify anything.

So do i need to buy a fuel pump filter separately Matt?

peadya100 wrote:Feisty haha
As much as I enjoy seeing Matt and Alexei debate, I'll just get a fuel pump to be safe. DW65c look good as i dont want to have to modify anything.

So do i need to buy a fuel pump filter separately Matt?

I bought genuine Subaru fuel filter from MRT (eBay shop) for ~$110.
Now I've seen "Genuine" filters for $70 on eBay which seems a good deal.

265 LPH e85 ready fuel pump with pre-pump sock filter for $125 from performanceshopint.com

I'm about to tackle the changeover myself this weekend. Wish me luck...

Good luck! Any photos and tips afterwards would be much appreciated

peadya100 wrote:Feisty haha
As much as I enjoy seeing Matt and Alexei debate, I'll just get a fuel pump to be safe. DW65c look good as i dont want to have to modify anything.

So do i need to buy a fuel pump filter separately Matt?

Ryco Z717 filter for around $60 or genuine filter for $100 and a few jars of Vaseline

Thanks Matt!

peadya100 wrote:Good luck! Any photos and tips afterwards would be much appreciated

Ok, all done. Took me about two hours. Was going slow and got stuck a bit on one thing (which I'll explain later).
I've taken the car for a short drive and everything seems ok so I'm calling it a success for now...

Sorry, no pics of my own. Flat battery in camera (grrrr!) and I didn't want to wait for it to charge.
Away there are some photos and help here:

http://forum.liberty.asn.au/viewtopic.php?f=12&t=16932

http://forum.liberty.asn.au/viewtopic.php?f=6&t=24840

And this has a good pictorial walkthrough (WRX but pretty much the same for Gen4) http://forums.nasioc.com/forums/showthread.php?t=2303133

The NASIOC walkthrough makes some good points. Safety first. Disconnect battery and have a fire extinguisher at hand.

You only need to remove the back seat lower squab. So everything is done from the drivers side rear passenger door area.
Seat removal is as easy as lifting at the two front connectors. No tools required, just a bit of force. Whole squab comes out.
Then follow above listed instructions.

My tips:
I had about 1/3 tank of fuel. Less would be better.
Opening fuel cap to release pressure means virtually no fuel leakage when pump lines are removed.
Fingers only are need to remove the fuel pump lines from the fuel tank.
You don't need to pull the wiring harness through the cover plate.
When you get to the part removing the actual filter from the retaining "bucket" (after the full assembly is out of the tank and after you take the circlip off the spring retaining rod) that's the best time to unplug the fuel pump power lead.

This picture shows a plastic o-ring "retainer" on the original pump. Retainer is below o-ring on pump.



This part did not come with my new pump or filter. The job would have taken me ~30 mins less if I didn't need to salvage it...
That's the hardest job - removing the old pump from the old filter to get that plastic piece out.
It takes 2-3 small flat-head screwdrivers, patience, perseverance and swearing - eventually the old pump will pop free.
You could probably double or triple o-ring on the new pump instead, I guess, but I decided to mimic the original install as close as possible.
Fitting the little metal retainer to hold the pre-pump filter to the fuel pump is also a pain. 2 small flat-head screwdrivers etc...

The rest of it is pretty simple. Do be careful of the fuel sender - it is delicate and exit/entry of the fuel pump/filter assembly should be done slowly.

When done I primed the pump 10 times - ignition on, but not cranking the engine - after that it started first time, no issues.

The old pump and filter didn't look too bad at all actually. The plastic was yellowed though. Also there was a bit of metal and debris caught in the old pre-pump filter.
It was obviously doing its job - so do not do an install without one of those!

If you have any questions, feel free to ask.

Brilliant write up. Thanks for the links too.
Let's hope it goes well for me