Fuel Pump/ Engine Studder Problems

[fsuskppy]

Car:
2004 Legacy 35 anv. ed (ugly stepchild)uses some 03,04 and 05 parts even though 05 is a different generation
78,000 miles
5SpM. Very Mild Upgrades
(pads, rotors, air filter, and cat back exhaust nothing drastic)

Problems:
For about the past three months when I would put gas in the car...full tank or one gallon doesnt matter...when I got about 200-300 yards away from the station the car would jerk lightly for about 10 yards and then drive normal.
Yesterday when I pulled off the highway...the engine would lope while at idle or low RPM until i reached around 3000rpm

After Troubleshooting in my haynes manual I really havent come up with anything.
All vacuum lines under hood: good/tight no leaks
Spark Plugs: normal/ w/proper gap
Timing belt looks fine
Fuel filter should be under the hood but its worked into the fuel pump unit in the tank. All auto parts stores says that parts not available.
I took the pump out of the unit and had these markings
UNISIA JECS
A42H04
020
3714N
I will post pictures of it tonight
I have looked at multipul websites and have come up with nothing
I need help from here? Do I need a new pump, filter, or just run the car off the cliff?

[rougeben83]

04 wrx's had the fuel filter moved to the tank. Maybe yours got moved there as well. There's no circular filter next to the washer tank? That's weird as my 03 has the filter in that location.

http://www.geocities.com/k91tsi/fuelfilter.JPG circled from an early WRX.

http://home.comcast.net/~k5shawn/sti/fuelpump.jpg in-tank fuel filter of later models.

Put that car in the "on" position (don't start it), you should hear a slight hum as the fuel pump primes itself. If you're hearing it after that or its very loud, that's a sign of a bad fuel pump.

[97scoob]

nevermind

[SubaGlue]

If it is your fuel filter, it IS NOT near the tank. It is exactly where that picture shows. I have an 01 BE (same gen) and I replaced mine a week or 2 ago. noticeably smoother and better response. I bought my filter for $21 at NAPA, and only needed a phillips and some elbow grease to remove the lines. (be careful fuel will spill everywhere :smt016 )

[Huffer]

If it is your fuel filter, it IS NOT near the tank. It is exactly where that picture shows. I have an 01 BE (same gen) and I replaced mine a week or 2 ago. noticeably smoother and better response. I bought my filter for $21 at NAPA, and only needed a phillips and some elbow grease to remove the lines. (be careful fuel will spill everywhere :smt016 )

Are you sure? I worked on an 04 Outback wagon and it's fuel filter was in the tank. It didn't have the in-line canister type near the washer bottle like on the previous models.

Just because it's the same gen (BE/BH) doesn't necessarily mean that everything is the same. Remember, 04 was the year they finished up the BE because the BP/BL was about to be released.

Subaru has this habit of part-exchanging across platforms during the year of transition ie. 95/96 BC-BD, 99/00 BD-BE, 00/01 RS, 03/04 WRX, 04/05 BE-BL...

[SubaGlue]

Im pretty sure, but I could be wrong (like I usually am). I wouldnt thing SOA would spend money to move the filter for a year or 2. Im pretty sure the JDM BE had it in the tank, but I also hear the JDM BE is a lot different than the USDM BE. You do make a logical point tho- that year in japanland the BP/BL was in production, so I suppose it could be in the tank :-? :smt017

[fsuskppy]

yea its in the top of the tank but it will cost $400 just to buy a new one so im just let the car sit for now and i cant afford to spend $400 and it not be the problem .......on the 04 (my personal findings/opinion)they used what i like to think of as "test parts" of the 05+ pretty much the only this the same between the 00-03 and the 04 is the body and the motor...everything else has literally been 05 part numbers...i even had to go with 05 brake pads and rotors

[rougeben83]

yea its in the top of the tank but it will cost $400 just to buy a new one so im just let the car sit for now and i cant afford to spend $400 and it not be the problem .......on the 04 (my personal findings/opinion)they used what i like to think of as "test parts" of the 05+ pretty much the only this the same between the 00-03 and the 04 is the body and the motor...everything else has literally been 05 part numbers...i even had to go with 05 brake pads and rotors

You can try and find the assembly from an 04 WRX, they would share the same assembly as you.