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Hi folks, i've been around on a few different forums and haven't had much luck yet so i'm gonna give USMB a shot. I've had this problem for 2 years ever since I bought the car, and recently decided to try to tackle it again.

 

Basically i can't fill gas, the pump keeps clicking off. It's just a real PITA.

 

I'm not throwing ANY CELs.

 

I know the possibilities are either the vent valve in the gas tank is not opening, or the hose to the charcoal canister is clogged. I've read it could be the pressure control solenoid which regulates the pressure in the fuel tank (not the purge solenoid), but I don't think that solenoid serves any purpose when the car is not powered on.

 

Last night I removed all three hoses from the charcoal canister, and drove to the gas station.

 

1) I expected to get a CEL, and i didn't. I know the light works. Any ideas of this? I know sometimes the ECM needs to detect a fault on a couple of trips, i turned the car on and off two or three times before i got to the gas station.

 

2) I still couldn't fill up, which indicates that it's not a issue with the canister or anything beyond the "Fuel Tank" port of the canister since i was venting directly to the atmosphere

 

3) Does this indicate the vent valve in the fuel tank is bad?

 

4) Would a bad solenoid affect the car while it's not on (and no CELs anyway)? Maybe stuck in a closed position?

 

Lastly, I found one of the hoses were broken that goes from the pressure control solenoid valve and Ts into the "Fuel Tank" hose. I tried putting a piece of fuel line tubing there but it didn't make any difference.

 

The PCSV has three nozzles on it, one that goes towards the "Fuel Tank" hose, one that pulls air in from the atmosphere, and one that comes from the shut-off valve all the way at the top of the filler neck. What is the purpose of the shut-off valve?

 

 

Thanks,

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Below are links to info that might answer some of your questions. One includes an example of the drive cycle requirements to trigger the CEL. Another details usage of a piece of equipment dedicated to EVAP system diagnosis (which might make plain why they can be a PITA :) ).

http://endwrench.com/images/pdfs/VehicleWont.pdf

http://endwrench.com/images/pdfs/EvapSpring04.pdf

http://www.endwrench.com/current/02SpringInsiderInfo.pdf

 

 

By the way, specific model info, etc., might help.

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Hey Thanks. I saw ferret's post but i don't think it's the the same issue since i disconnected all the hoses and vented it to the atmosphere but still have the problem.

 

I've scoured all corners of the internet for a definitive answer, the dealer wants 100 bucks to diagnose it.

 

 

Haha that one link is some really intense stuff with the diagnosis machine... I've read the first link there and think i've ruled out clogged or kinked hoses.

 

My car is a 1996 Subaru Legacy L Wagon

Edited by shortskoolbus

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Also, i noticed that ferret says the drain valve is to let air out, but actually I believe it's to let air in. It's usually closed, and when energized it OPENS to let air into the canister. It will get energized by the ECM when the purge valve opens it needs to allow air in from the atmosphere in order to maintain the pressure within the EVAP system.

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Check your charcoal canister, does it feel heavy?

 

If you have topped off the tank recently and it sucked in some fuel, it can cause this problem.

 

Have you checked the two-way valve (by the charcoal canister).

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Check your charcoal canister, does it feel heavy?

 

If you have topped off the tank recently and it sucked in some fuel, it can cause this problem.

 

Have you checked the two-way valve (by the charcoal canister).

 

I disconnected all the hoses from the charcoal canister and still couldn't fill gas, so i don't believe that the problem is at the canister.

 

I guess that's the pressure control solenoid valve, that one is supposed to be closed when not energized i believe? So i don't think that would make a difference.

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No, this is a rinky dinky little check valve in the rubber line by the charcaol canister. Looks like a check vlave of some sort. If you follow the lines from the canister it should be about 12" or less away.

 

nipper

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i had this problem with a toyota...

 

i thought it was an issue with the pressure int eh tank so if you started the car wiht the gas cap open, it would eventually fix the problem..

 

 

either it worked for me or it was coincidence..

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Hmm that never occured to me, maybe i'll try filling up with the car on and see if that makes any difference.

That's not a good idea. At a minimum, if OBD is working correctly, you can get a CEL indicating an EVAP fault (since with the engine running, the tank shouldn't be at atmospheric pressure). Also, given that apparently the tank venting isn't working correctly, who knows what path the gas might take with the engine running. I won't get into possible safety or legality issues, which would probably just start a debate.

 

Unfortunately, if the vent valve is indeed the problem, it will require lowering the tank to deal with that. Before 'going there', if you have the time and patience, it would seem verifying that all the EVAP and gas tank-related tubing is properly connected/routed and free of obstructions might be prudent.

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If you live in a cold climate the extra fuel vapors that are going to the charcoal filter could contain moisture and end up freezing in the canister preventing any new fuel from entering the tank. I have our 2005 OB in our heated garage as I type. I am unable to fuel up also. The shop told us about the moisture problem. I am going to thaw it out first, and if that solves the problem next thing is to change the charcoal filter just in case it might happen again not so close to home.( temperature right now -22 with wind up to 30 mph.)

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It could just be the vapor recovery nozzle on the gas pump. Make sure it seals completely.

 

Sometimes you will have to hover the nozzle or hold it sideways or at weird angles to work. I encounter this now and again at other places that have them more and i am always driving old cars.

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I have a 2004 Subaru forester and have been having the same issue trying to fuel up and the tank not venting properly.  I have fixed it once for a short time and just fixed it again the same way by removing the solenoid valve located just to the right of the evap canister behind the right rear wheel.  When attempting to blow through this valve it was not letting much air in.  Gave it a tap and that freed up the valve.  I put everything back in shot to the gas station and filled it up like a dream.  Took it back today to show the wife what a good provider I was and what would you know it did not work again.  When I pulled the valve off it was stuck again.  A little rap and it was free.  I think the control system usually keeps this vent on low flow and when you are filling it is supposed to open up to allow venting of gases through the canister.  I also think it is in line before the canister so removing the lines at the canister did not help you. (I tried that 1st as well.)  If it is in the same location as mine you should see a larger diamer 'S' shaped hose coming off of the canister and going up to a valve with an electrical connection (this is the one you want to check).  On the other side of the valve the hose goes up to a vent filter which is just a large open can (I expect to keep liquid and debris from clogging the lines as there did not appear to be any filter material inside.  the hose after the filter then returns to the tank.  I think if you wanted to do a quick check you could pull the hoses off at the solenoid valve and try filling then.

 

To keep this from reoccuring I will be heading off to see how much a replacement valve is going to cost me.  I am guessing I will still be saving money avoiding the diagnostic charges and install work from the dealer.

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