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Guest Message by DevFuse
 

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Fuel Filter 2005 OB

fuel trim fuel pump P0420

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8 replies to this topic

#1 brus brother

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Posted 20 July 2013 - 08:28 AM

OK a little late on maintenance at 135K miles, I decided to check out the fuel filter.

Turns out the only fuel filter is a "sock" inside the gas tank and according to SOA tech "we never change them".

Anyone change/examine yours?

While on the subject, this week I will be visiting a mechanic to track down the cause of an elusive P0420 that a data log interpretation is pointing to either vacuum leak or poor fuel delivery (perhaps both if I'm really unlucky?).

Mechanic plans on "smoking" the car in search of any vacuum leak and then checking fuel pressure.

Would you check pressure first or it doesn't matter?

Few questions:

1. Can a fuel pump be failing (weak) without obvious symptoms over a period of 2 years and 30K miles?

Since the dealer doesn't stock the pump, is this easily replaced?

Any directions appreciated.

2. Where is the fuel pressure regulator?

Same question about failing/weak fuel pressure regulator symptoms??

3. Can the "sock" filter become coated and therefore ineffective? Doesn't look like it is replaceable.

 

 



#2 grossgary

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Posted 20 July 2013 - 02:38 PM

the fuel filter in 2005 moved to inside the gas tank. it's under the rear seat bottom cushion.  remove cushion (like 2 12mm bolts), remove access cover and then fuel pump.  30 minute job.    the sock is on the bottom of the pump and indeed no need to touch it.  fuel filter won't be an issue either but easy enough to replace if that's what you want.

 

pumps are easily replaced, but insanely expensive and i don't trust aftermarkets yet. 

 

i'd check fuel pressure just because it's easy ( have no idea how expensive a smoke test is, but can i join him?! LOL).



#3 brus brother

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Posted 20 July 2013 - 07:00 PM

Yup, pump is $300 discounted from FirstSubaruPartsForyou.com. They are local for me but don't stock the pump. I am confused, from your post, it seems there is the "sock" AND a fuel filter also... or are they the same?

Any need to depressurize the tank before opening? Pull pump fuse and run till stall??

Anyway, fuel pressure test first. I sprayed brake cleaner around all of the hoses today and didn't get any rpm surge. I don't hear any exhaust leak but when the car is running the exhaust makes enough sound to drown out others.

the fuel filter in 2005 moved to inside the gas tank. it's under the rear seat bottom cushion.  remove cushion (like 2 12mm bolts), remove access cover and then fuel pump.  30 minute job.    the sock is on the bottom of the pump and indeed no need to touch it.  fuel filter won't be an issue either but easy enough to replace if that's what you want.

 

pumps are easily replaced, but insanely expensive and i don't trust aftermarkets yet. 

 

i'd check fuel pressure just because it's easy ( have no idea how expensive a smoke test is, but can i join him?! LOL).



#4 grossgary

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Posted 21 July 2013 - 07:23 AM

Yes it has a sock AND a filter.  Subaru's have always had fuel socks..or at least for 4 decades no that I know of, they're just generally ignored and not talked about unless you have a terribly rusty fuel tank or something like that you'll never see on such new vehicles. They're always built in and on the uptake side of the fuel pump, even in older 80's stuff where the fuel pump was external and completely different.

 

Yes do as you say with fuel pressure, probably a good idea.  A small amount of fuel sprays out when you remove the fuel lines.  It's not much and I ignore it, not worth my time to depressurize, but since this is in the cabin I can see how some folks would want to do it first.  The gas still doesn't get "into" the cabin since the hoses are accessed through a plate and still "outside" the cabin.  but the fumes will of course get in the cabin for a small length of time. 



#5 Fairtax4me

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Posted 22 July 2013 - 01:04 AM

The strainer on the pump almost never clogs unless someone put sand in your tank.

I'd check fuel pressure first before chasing fuel pump issues. The new style pumps have a built in filter which is not easily replaced, nor is there any after market parts support for them yet, so probably impossible to find. Same goes for the strainer.

#6 brus brother

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Posted 22 July 2013 - 08:55 AM

Is there a pressure regulator on 05 Outback USDM? Passenger side under intake manifold? Other than regulator and pump, what could affect fuel pressure? I ran some more logs and these now appear much different than original! Would pressure reg fail slowly/intermittently?

#7 grossgary

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Posted 22 July 2013 - 09:47 AM

Porcupine (member) says rear passengers side of the fuel rail on his 00 - 2 screws and 5 minutes.  another member said front drivers side of fuel rail on an 04 H6.  which is all about the same as they've been for decades so you should see it on the fuel rails...unless of course it's got a zillion covers over everything.

 

here's a guy that had lean fuel conditions and had to replace his fuel pump on an 06:

 

http://www.subaruout...l-pressure.html

 

 

looks like the regulator at some point was built into the pump right around 05/06 and no longer in the engine bay...not sure when though?

 

makes me wonder if i can "upgrade" to the new style pump with built in regulator and no "cap" that fails on the 00-04 models?



#8 macnore

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Posted 01 July 2014 - 08:15 PM

I had a problem with fuel supply and thought it was the fuel filter. But doing some research I came across a thread that warned against over filling the fuel tank. I was in the (bad) habit of squeezing as much gas in the tank as I possibly could and in doing so the extra fuel ran in the overflow and in to the CAT which will cause premature failure of the CAT. Try not to over fill your tank if indeed this is something you might be doing. Maybe the raw fuel will burn off  and things will return to normal. It is possible that your rear O2 sensor will need replacing.



#9 Fairtax4me

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Posted 01 July 2014 - 09:53 PM

The overflow doesn't go into the cat. It goes into the evap charcoal canister. The canister is made to absorb fuel vapor, but liquid fuel will saturate the carbon in the canister and can cause the carbon structure to fall apart. Once the carbon is saturated it can not release all of the fuel, which prevents it from absorbing any more fuel vapor.





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