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View Full Version : Don't re-use the in-tank filter, convert to in-line filter instead



BrandonDrums
09-25-2013, 04:08 PM
So on some of the build threads, guys with post '04 donor cars are trying to figure out what to do about the in-tank fuel filter. On WRX's from 02-04 Subaru used an under-hood fuel filter that looks like this.
http://www.1stsubaruparts.com/catalog/images/subaru%20fuel%20filter.jpg

On the STI and WRX's after 05, they use a 'permanant' in-tank fuel filter. Initially there wasn't even an individual part number for the in-tank filter by itself, subaru said it didn't ever need to be replaced and only was sold with the full in-tank assembly. Now they just try to charge you for the whole housing and canister but you can buy the canister/filter media by itself. http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/112058-sti-fuel-filter-pictures-w-disassembly.html

I did the conversion at 90k. When I got the original filter out of my car and cut it open, I found it was made out of basically rolled up cardboard and was filled almost completely with sediment. Like I said though, the STI's and 06-07 wrx's have a nicer filter but the PITA alone to need to pull the pump out of the tank to replace the filter is enough to consider doing the conversion.

It's easy. Just remove the filter from the in-tank assembly and replace the span between the pump and the fuel tank plate nipple with a corresponding length of Fuel-grade 3/8'' line (I think it's 3/8'' at least). Next you just take the old canister type filter and pop it in-line on the top fuel hose going to the engine.

Here's what your in-tank assembly will then look like after removing the in-tank filter:
http://home.comcast.net/~k5shawn/sti/fuelpump.jpg

Here's how you can install the filter keeping that little magnet damper thingy, I removed mine since they don't really do anything. It goes on the top line connecting to the engine.
http://subyencore.files.wordpress.com/2012/09/2012-09-04-19-31-22.jpg

Doing this will save you a few bucks and make it a lot easier to change your fuel filter more regularly.

RM1SepEx
09-25-2013, 04:29 PM
Brandon, you can't reuse the in tank filter, it only has one end with a hose fitting... as described in a couple of our build threads... I bought the earlier filter at Napa for $20 and mounted it over my fuel tank

21787

I made a .050 aluminum clamp and attached it with a couple riv-nuts over the fuel level sender

Bob Cowan
09-25-2013, 04:32 PM
I wouldn't just remove the filter. An electric pump needs some sort of pre-filter to keep the big junk out. something with at least a 100 micron rating. Otherwise, small particles that get into the gas tank will destroy the pump.

RM1SepEx
09-25-2013, 04:59 PM
the tank has a fine mesh sock prefilter that you can see in his photo above.

BrandonDrums
09-26-2013, 07:57 PM
Brandon, you can't reuse the in tank filter, it only has one end with a hose fitting... as described in a couple of our build threads... I bought the earlier filter at Napa for $20 and mounted it over my fuel tank

21787

I made a .050 aluminum clamp and attached it with a couple riv-nuts over the fuel level sender

Depending on the year, you're correct that you can't re-use the filter catridge assembly....which was what I was pointing out with this post. In later years and on the STI, the in-tank filter did have a twist off function to allow you to replace the filter media as a cartridge type filter. Regardless, my entire post was about how it's better to do what you're saying...which again is what I also said which was to covert to the in-line filter from the 02-04 wrx...

Here's a thread that I shared above showing how later model years and the STI have a re-usable in-tank filter housing for a cartridge http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/112058-sti-fuel-filter-pictures-w-disassembly.html

Here are the pictures from that thread showing the re-usable canister from 06/07 and STI models. The 05 WRX doesn't have this and it's possible some other factory models also have the 'permanant' filter which is made of cardboard and doesn't twist apart.

http://www.bescaredracing.com/sti/fuel/filter/DSC09365.JPG
http://www.bescaredracing.com/sti/fuel/filter/DSC09369.JPG
http://www.bescaredracing.com/sti/fuel/filter/DSC09378.JPG

BrandonDrums
09-26-2013, 08:06 PM
Brandon, you can't reuse the in tank filter, it only has one end with a hose fitting... as described in a couple of our build threads... I bought the earlier filter at Napa for $20 and mounted it over my fuel tank

21787

I made a .050 aluminum clamp and attached it with a couple riv-nuts over the fuel level sender

Right, it just sounds like FFR didn't specify HOW to get rid of the in-tank filter which I guess can be the point of my post. However I did read somewhere that someone was asking how to replace the in-tank filter. Folks trying to do so should do the conversion as you did. I don't have an 818...yet...so I haven't read the whole assembly manual. Just sharing.


I wouldn't just remove the filter. An electric pump needs some sort of pre-filter to keep the big junk out. something with at least a 100 micron rating. Otherwise, small particles that get into the gas tank will destroy the pump.


The OEM in-tank filter is actually post-pump. The mesh 'goldfish net' pre-filter is what's there to protect the pump.