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Old 10-23-2012, 02:44 AM   #1
I3eXa
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Default Fuel tank issue

2004 OBS, has a stock 15.9gal fuel tank. It runs out at about 260-280 miles, at almost exactly the 1/4 mark on fuel gauge. Fill it up and it only takes 12.9ish gallons so why am I not getting those last few gallons?? Also, when it's real low and I take a hard left turn and straighten back out it fuel cuts for a second or two before it kicks back in and continues to accelerate.
Shouldn't be fuel filter-new within 5K miles
Fuel pump?
Sender unit?
Injectors?
Some filter in the tank?
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Old 10-23-2012, 03:00 PM   #2
GrundleJuice
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Did it just stay doing this or has it been like this all along? My 07 had a 15.5 gal tank, the low level light comes on at "E" but I rarely get it to take more than about 13 gallons unless I keep topping it off. Does your low level light come on?

Could be lots of things but you will have to open the tank either way. Pull the back seat, open the access panel and remove the pump/sender assembly. See what you can see. See?

Edit: not sure if the obs tank access is the same, but it should be similar
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Old 10-23-2012, 05:27 PM   #3
I3eXa
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Been like that ever since I bought it. Yeah access should be the same but just looking I doubt I'll see the issue since I assume its electrical no low level light comes on either
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Old 10-23-2012, 06:58 PM   #4
alt14
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When you fill it up to about 12.9 gallons does it completely run out of gas? I know that my gauge is really inaccurate and stays around 1/8 of a tank even though I have nearly four to five gallons left. And also when you fill it when it is almost all the way out is maybe the pump your going to sensitive? I've been to a few that cut off even though I still have a few more gallons to go(i'm assuming from faster flowing pumps splashing the gas back up to trip it) Does your pump sound louder when you have a fuller/emptier tank or can you not hear it at all?
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Old 10-23-2012, 08:34 PM   #5
I3eXa
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I can hear that it's full and have used different pumps before.
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Old 10-23-2012, 10:21 PM   #6
GrundleJuice
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If you pull the pump/sender assembly you might find a broken pickup or something. That would explain why it "runs out of gas" with 2 or 3 gallons left, and displays 1/4 tank tank no low level light comes on. Do it when it's just about to run out again to verify that there is actually still a cpl gallons left. That would rule out a stuck float.
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Old 10-23-2012, 11:16 PM   #7
I3eXa
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Awesome. Thanks for the input. Ill give that a try next time it's empty
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Old 11-29-2012, 11:05 PM   #8
I3eXa
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ok so I remembered to leave the tank empty and took a peek at the fuel pump assembly.
Looked ok.
The tank actually looked pretty empty which is weird but not sure if it's supposed to look like that and I didn't take a picture!
The fuel pump strainer looked brownish n dirty but the float seemed to move freely and work fine so I still have no idea.
No noise from the fuel pump but I'm not sure if I should just replace it and the strainer and see where that leaves me....any more ideas?
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Old 11-30-2012, 03:29 PM   #9
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Quote:
Originally Posted by I3eXa View Post
ok so I remembered to leave the tank empty and took a peek at the fuel pump assembly.
Looked ok.
The tank actually looked pretty empty which is weird but not sure if it's supposed to look like that and I didn't take a picture!
The fuel pump strainer looked brownish n dirty but the float seemed to move freely and work fine so I still have no idea.
No noise from the fuel pump but I'm not sure if I should just replace it and the strainer and see where that leaves me....any more ideas?

OEM fuel strainer is solid. I'm not sure if your pump is the same as a 03 wrx, but if you pm me maybe we can talk a little bit? I upgraded to a walbro 255 a few months ago so my stocker is just laying around.
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Old 11-30-2012, 04:04 PM   #10
I3eXa
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I can't figure out how to PM from my iPhone but I think I'm just gonna order a new one with a new strainer and throw it in on a rainy day. Not sure if it will do me a lick of good but I have no clue what else it could be
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Old 11-30-2012, 05:25 PM   #11
jthatch12
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Originally Posted by I3eXa View Post
I can't figure out how to PM from my iPhone but I think I'm just gonna order a new one with a new strainer and throw it in on a rainy day. Not sure if it will do me a lick of good but I have no clue what else it could be
If you do order a new strainer, go OEM. But honestly, I'd say the fuel strainer will most likely do nothing. When I replaced my pump, my strainer was also amber in color, I used that one anyway
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Old 11-30-2012, 07:12 PM   #12
I3eXa
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If you do order a new strainer, go OEM. But honestly, I'd say the fuel strainer will most likely do nothing. When I replaced my pump, my strainer was also amber in color, I used that one anyway
well all the stuff I've read says your warranty is voided on the fuel pump unless you purchase a new strainer as well fyi. I will go oem for the strainer but should I do the same for the pump?!? To frickin expensive!
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Old 01-19-2013, 07:26 PM   #13
I3eXa
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ok so I've replaced the fuel pump assembly with the sender unit on it and also replaced the sender unit/float on the driver side of the tank and it hasn't emptied yet but it looks like it's doing to same thing. Any other ideas? Not that I really care how the gauge reads but I'm going to take it on a trip in a week and hate that I only get like 250 miles per tank
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Old 01-20-2013, 10:17 AM   #14
Elbert Bass
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Quote:
Originally Posted by I3eXa View Post
ok so I've replaced the fuel pump assembly with the sender unit on it and also replaced the sender unit/float on the driver side of the tank and it hasn't emptied yet but it looks like it's doing to same thing. Any other ideas? Not that I really care how the gauge reads but I'm going to take it on a trip in a week and hate that I only get like 250 miles per tank
Ouch. Wish I had seen this before you bought a pump. These cars have a saddle tank that straddles the rear driveshaft. It creates a siphon with the return fuel pressure (in the pump assembly) to suck the last bit of gas from the left side of the tank. The siphon is not made by a pump, it is a plastic fitting that works off pressure differential to draw the fuel.

Pull the inspection cover from the drivers side to gain access to the left fuel level sensor/ fuel pick-up. You could have a clogged line from the pump assembly to the left pick-up, a broken or clogged pickup, a broken siphon (in the pump assembly). You will need to run it to E and then look and see how much fuel is in the left side compared to the right side. if there is a big difference you have siphon problems.

Last edited by Elbert Bass; 01-20-2013 at 01:25 PM.
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Old 01-21-2013, 04:31 PM   #15
I3eXa
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thanks. It was a used pump from the junkyard so I can return it when I get the time to swap it back out but when I swapped out the driver side fuel lever sensor I didn't take that great of a look but didn't seem like it had much more than the other side. Guess I'll inspect some more next time I'm empty.
Appreciate the info though as it gives me alittle bit better insight into how it works. Unfortunately I'm guessing that I'd have to drop the tank to get to those lines between the two sides of the tank huh?
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Old 01-21-2013, 05:48 PM   #16
Elbert Bass
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Quote:
Originally Posted by I3eXa View Post
thanks. It was a used pump from the junkyard so I can return it when I get the time to swap it back out but when I swapped out the driver side fuel lever sensor I didn't take that great of a look but didn't seem like it had much more than the other side. Guess I'll inspect some more next time I'm empty.
Appreciate the info though as it gives me alittle bit better insight into how it works. Unfortunately I'm guessing that I'd have to drop the tank to get to those lines between the two sides of the tank huh?
There is a hard line (metal tube) that traverses the top rear of the tank, but the two hoses on each end that connect to the sending units should be accessible in-car. The only reason you would need to drop the tank would be if the hard line was crushed, rusted through, or punctured.

If you had to drop the tank sometimes you can just lower the rear cross member with rear diff and axles attached and swing the tank down on the cross member enough to reach the plumbing and vent system on top of the tank..
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