2006 Outback wagon 2.5i low fuel pressure - Subaru Outback - Subaru Outback Forums

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Old 07-11-2013, 12:02 PM   #1 (permalink)
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Default 2006 Outback wagon 2.5i low fuel pressure

I have a 06 outback wagon 2.5i. Non turbo with about 147k on it which has been giving us trouble starting lately. Long crank time to start. The car also has thrown a CEL code p0171 too lean. I have done a whole series of things to try and fix this. Including checking the air supply duct, new air filter, spark plugs, clean the MAF. Cleaned the throttle body by removing it. I also changed the front a/f oxygen sensor Finally checked the fuel pressure got about 18 psi with key on and 25-28 psi while running. Spec says 49-53 psi I believe.. Don't have the book right here now. So I am running at about half. I also connected my vag com cable and saw the fuel trims going to like 10-25%.

I cannot find the fuel pressure regulator. I fear that it is part of the fuel pump.

What is the little valve bolted to the center of the intake manifold? It has an electrical connection and a fuel line in/out connected to it. I think I read it was a purge valve. I disconnected the wire to it and saw no effect. I did not check if I got any new codes to determine what the device is.

Any input is appreciated.
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Old 07-11-2013, 03:58 PM   #2 (permalink)
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I wonder if this is the start of a new crop of fuel-pump in-tank-filter cap/o-ring failures?
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Old 07-11-2013, 06:10 PM   #3 (permalink)
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Quote:
I wonder if this is the start of a new crop of fuel-pump in-tank-filter cap/o-ring failures?
I guess it's possible.

However, I believe it was around MY2006 that a change was made to the fuel routing. There's no longer a fuel pressure regulator on the engine fuel rail. This also involved a different fuel pump assembly with built-in fuel regulation.

The reason for the change was to prevent fuel returning to the tank (from the engine compartment fuel pressure regulator), which could be warmed up by engine heat, from warming the fuel in the tank, leading to excessive evaporation.

With 2006, there's two fuel-type hoses coming up the left side of the engine compartment -- one is the fuel supply, the other is the vapor line going to the purge solenoid valve (on the intake manifold).

On earlier models, there's three hoses; the third is the regulator return line back to the tank.

Rock Auto shows photos of two distinctly different fuel pump assemblies; the one with the failing cap for earlier models, and another for 2006.
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Old 07-11-2013, 09:47 PM   #4 (permalink)
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Pull the pump and check the regulator cap for a swollen seal or cracked cap. If the regulator looks good, replace the pump.
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Old 07-12-2013, 07:05 AM   #5 (permalink)
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No cap on 2006. Also note there's only two hose fittings at the top on the 2006 pump, for the fuel out and the transfer line from the left side of the tank. Earlier pumps have 3 fittings; the additional one is the fuel return from the pressure regulator up front.







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2006 Outback wagon 2.5i low fuel pressure-2004-pump.jpg   2006 Outback wagon 2.5i low fuel pressure-2005-pump.jpg   2006 Outback wagon 2.5i low fuel pressure-2006-pump.jpg   2006 Outback wagon 2.5i low fuel pressure-2001-pump.jpg  
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Old 07-12-2013, 07:16 AM   #6 (permalink)
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Thanks plain. Too many changes in a short time. Don't know what I was thinking.
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Old 07-12-2013, 12:14 PM   #7 (permalink)
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Thanks! I have only two lines returning up front so sounds like the regulator is in the tank. I assume there is no top access to the tank like in my VW. It looked ugly to drop the tank.
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Old 07-12-2013, 12:27 PM   #8 (permalink)
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Access is from inside the car, under the rear seat. There are removable hatches in the floor pan over the pump (right side) and the sub-level pick-up (right side).

As far as I know, parts of the pump assembly cannot be replaced separately. If there's a fault in the pump the whole thing will probably have to be replaced. But if you find otherwise, let us know.

Seat removal, see attached.
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Old 07-12-2013, 06:40 PM   #9 (permalink)
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That is some very good news. I appreciate the info. Now I have to decide if I want to buy an OEM pump or aftermarket. Warranty would probably be a decision maker.. Looked like $300 or so...
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Old 07-18-2013, 04:52 PM   #10 (permalink)
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Bought a pump at my local dealer. Got 20% off. List price was $436.95. Paid $349.56 plus tax. Part number was 42021AG12A. It is the complete fuel pump asy. with filter and fuel gauge sending unit. No gasket included, but the original looked pretty nice. It looks just like the rockauto 2006 photo. Has two fuel lines only. Was a pretty easy job aside from it being 98 deg outside.

The car is starting up fine now and no cel for 2 days. I am going to retest the fuel pressure to see where it now. I popped apart the original fuel pump to see if I could find anything obvious and did not notice anything. Very little dirt at the filter.. Some metal shavings and a little debris.. Pretty clean otherwise..

I did see the same pump on amazon for $275 del. ... I was a bit paranoid about my wife driving the car around with a potential true lean condition and damaging something major. So we limited use until I installed the pump.

Thanks again for all of the quick responses. I am keeping the old pump in case I determine the failure or scavenge it for the fuel sending unit, or whatever. I wonder what the warranty on the new pump is for the stealership?
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