P0440 and filler pipe

[Mikevan10]

MIL code P0440 popped up on my 1997 Legacy 2.2 station wagon.  I searched this forum and based on what I read the first thing I checked was the condition of the fuel filler pipe.  The bottom of the plastic cover was packed with dirt and the pipe showed corrosion on the o.d.  It also looked slightly damp but I couldn't tell if it was fuel leakage or just moisture from the dirt.  I tapped the rusted area very lightly with my wrench and immediately got drips of gasoline.  So I think it is very likely that there were pin holes in it.  So I have procured a new filler pipe (Rock Auto $87.22 with shipping).

 

My questions for y'all kind folks:

 

1.  Gas tank is full.  Will I get doused with fuel if I disconnect the pipe from the tank?  If so, how much gas do I need to siphon out before it is safe?

2. Any tips on the procedure in general?

3.  How does the computer know that there is a breach in the integrity of the system?

 

Thanks!

 

Mike V.

[PA Grown]

1 safety first just drain the tank with the drain bolt and use a light coffee filter when you're done to clean the gas after its drained. My 94 has a 11 gallon tank so get a big container.

2. If you've got a gas leak you're probably sucking air and whatever else is going through the hole when the fuel pump is running, like dirt. So you should probably clean your fuel system as a caution. Get as in depth on the cleaning as you feel is necessary. If you think there's air in the system pull the fuel line from the fuel filter and crank the engine.

[Mikevan10]

So, you are implying that the filler pipe enters at the bottom on the tank?  If so, I'll obviously HAVE to drain the tank.  Removing a drain plug sounds like a great opportunity for additional (bigger) problems so I will first see how much I can remove by siphoning...

 

Thanks.

[Rooster2]

I recently had a friend replace the filler pipe on both my 98 & 99 Outbacks, as both were rusted and leaking. He did most of the work, I was his "helper." No need to drain the gas tank, as the pipe connects at the top of the gas tank, so no gas is going to leak out. The 94 and 95 models are different car bodies. Maybe the 94 needs to be drained, I don't know, but not with 95-99 models. If still unsure, pull the road wheel to get a good view of exactly where the fill pipe enters your gas tank. It will be easy enough for you to see.

 

I disagree with PA Grown.......yes, the holes in the filler pipe prevent the needed vacuum effect for best fuel pumping. However, the vacuum leak is minor, and not strong enough to suck in dirt along with air. The situation created is hard on the fuel pump, and prolly affects its longevity. Also, I don't think air is able to enter the fuel line, so no need to pull the fuel line from the fuel filter. Also, upon pipe replacement, I did not replace the plastic enclosure around the pipe, seems like more trouble then it is worth.

 

It may be a good idea to replace the fuel filter. It is easy to do. Replacing the fuel filter on my 99 resulted in a much stronger running motor, so they do get clogged up over time.

 

Yes, the computer senses there is a vacuum leak and will set off the PO 440 code. Removing a battery cable for 5 minutes, then re-install will remove the code, and cancel the check engine light warning on your dashboard.  Of course, if your have a code reader tool, you can remove the code using the reader tool as well. 

Edited November 8, 2014 by Rooster2

[Mikevan10]

Thanks a lot Rooster!  I will let y'all know how it goes...

[Mikevan10]

Hey, why didn't anybody mention that tis job is a royal pain in the butt!

 

Couple more questions:

 

Do you detach the main filler pipe from the other pipe and install them separately and then, SOMEHOW, connect them back together?

 

Do you insert the main pipe into the hose on the tank before you swing the pipe up and put it through the hole in the body (by the filler cap) or vice versa?  It seems like if I insert one end in I then can't get the other end in.  I have tried both ways with no success.

 

Any other suggestions?  Drop the rear axle assembly???!!!??

Edited November 8, 2014 by Mikevan10

[Mikevan10]

Alright, I think I got it.  More later.

[Mikevan10]

OK, here's my recap and suggestions:

 

Filler must enter to of tank because no fuel spilled when I disconnected pipe even though tank was full.

 

The hardest part of the disassembly/removal was getting the hose clamp of the hose that connects the small pipe to whatever pipe it connects to.  I removed the sway bar to body clamps to facilitate this but getting pliers on the spring type clamp was a bear.

 

I separated the main pipe from the small pipe to install (I believe this was necessary).

 

I installed the small pipe first. 

 

I inserted the main pipe through the hole in the body and then connected the tank hose to it.  Getting the hose on was not easy but eventually doable.

 

Connecting the small pipe hose to the spigot on the main pipe required loosening a couple of the hose clamps to gain some freedom of movement.  This was tricky due to the orientation of the clamps as received on the new part.  Repositioning of these clamps before installing the small pipe would have helped due to the extremely limited access to the hose clamp screws...  I recommend looking this over before you install the small pipe.

 

The above is trickier than it sounds.  This is a "fiddly" job, to say the least.

 

When I finished I disconnected the battery for about 1/2 hour in hopes of extinguishing the MIL but as soon as I started the car the light remained on.  It came on when I cranked the starter and stayed on.  So it seems like disconnecting the battery did not work.  It's not like the light wasn't on when I started it and then came back on.  I would assume that there would be a delay before whatever senses the lack of vacuum or else you would get the light every time you fill the tank.

 

Any suggestions?

 

Thanks,

 

Mike V.

[Rooster2]

Mike,

 

Happy to hear that you installed your filler pipe after a lot of cussing, I am guessing. Your CEL sensing a vacuum issue may be due to a bad gas cap. If your cap is old, the seal may not be tight, so it creates a vacuum problem. Unfortunately, replacement gas caps don't have the OEM teather, if bought from a parts store. More then once, I have left my gas cap at the service station, and had to go back to retrieve it.

[Mikevan10]

Thanks again Rooster.

 

So does solving P0440 come down to a sort of shotgun approach?  Seems this is a nasty one to overcome.

[Mikevan10]

Also, where is the vacuum sensor located?

[Rooster2]

Thanks again Rooster.

 

So does solving P0440 come down to a sort of shotgun approach?  Seems this is a nasty one to overcome.

Yes, it is a shotgun fix approach. Newer diagnostic systems tell you exactly what part is malfunctioning. Obviously, Subies from the '90s aren't that sophisticated. I have never though about, or heard where that sensor is located. The PO 440 lights up on many Subies. Usually, it is a bad gas cap that is the source of the vacuum leak.

[heartless]

not really sure about the cause of that P0440 code - but I have a leak in my tank - replaced the filler neck and that isnt the problem - mine is in the actual tank and I have NEVER seen the P0440 code on my 95...

[Bushwick]

The entire evap system needs a going over. It's possible a vacuum leak or the charcoal canister is leaking around the same time you discovered the filler neck leak. I recently found a vacuum line with a hidden split so decided to replace all surrounding vacuum lines to be safe as they are original and most were rock hard on the bends. When I got to my charcoal canister, I popped off the 1-way check valve right near the opening to the canister and discovered it was seized in the "open" position. This means when fumes from the tank were forced into the canister, the valve is supposed to prevent the fumes from backing up in the line or evacuating the canister through the wrong port. It's failure will reduce the efficiency of the fumes being drawn across the charcoal and eventually burnt in the combustion cycle (assuming I'm understanding correctly as this isn't a study I memorize). I had no CEL, and no physical warnings i.e. no noxious gas odors other than a less than ideal idle. After replacing that valve and the vacuum lines, engine idles a little higher after just starting (in Neutral) then holds a more constant idle in gear. The charcoal canister is apart of the entire evap system, and it's easy enough to get at. Also, it's worth checking the line that runs from the tank to the engine area for breaks (dunno if Subaru uses a rubber vacuum line or what) but whatever it uses to draw excess fumes from the tank, inspect it. It it's disconnected, the fumes will never go where they are supposed to go. On gas caps, it's usually the rubber O-ring that fails first. Inspect it's not rotted. 

 

 

Also, I strongly suggest replacing the fuel filter for $15. Dirt in the tank or contaminants can make it to the filter, and clog over time. If heavily impacted, it'll starve the engine and overwork the fuel pump. 

Edited November 10, 2014 by Bushwick