gas pump acts like fuel tank is full

[jayiszraw]

when i fill up the pum starts to act like its full i believe its an issue with the evap ssytem and the face that it may be clogged. also i remeber redaing something about the rising rate fuel system useing evap lines for a return? more info on that plase? also how can i go about trouble shooting my issue becuase it gets really annoying to fill up.

[hercfe]

if you run it all the way empty, especially in the summer, you can effectively vapor lock the evap system. it happens on every car, but for some reason turbo cars seem to be more susceptible to it. i'm pretty sure the owners manual even says something about it. topping off the tank can also cause this as it can damage the vapor recovery on the pump itself, but it can also clog the evap canister sometimes. i know most of this doesn't really help, but rest assured you're not the only one. if you have a clogged evap, you WILL know. its a hard code that will give a cel immediately.

[djs]

It's happened to me a few times, really annoying. I usually try to get about a gallon into it and drive it a few miles, seems to free up the system.

[old guy]

Read this: Clicky click

[jayiszraw]

are there any diagrams for this to help me disconnect the correct line?

[old guy]

are there any diagrams for this to help me disconnect the correct line?

I don't have any in my bookmarks, but if you remove the cover plate it should be fairly intuitive if you read the descriptions provided in the link.

Good luck!

[jayiszraw]

grave digging for an update to help someone out in the future, i removed the bigger line of the two and i fuel up just like its supposed to. so is that the evap canister that neeeds to be replaced??

[old guy]

grave digging for an update to help someone out in the future, i removed the bigger line of the two and i fuel up just like its supposed to. so is that the evap canister that neeeds to be replaced??

It's one of two things. It could be a clogged canister or a non-functional LDP valve. Are you getting any LDP codes? The next thing to try would be to hook the large line back up and the next time you go to fill the tank up disconnect the small line that goes from the canister to the LDP. If the problem returns, replace the canister. If the problem goes away with the small line disconnected it would indicate that the LDP isn't functioning properly. The pressure normally vents through the LDP paper filter located underneath the drivers side rear wheel well when you are filling the tank. So either the canister is clogged or the LDP won't let the canister vent.

Usually the problem is with a clogged canister. Some models also have a cylindrical filter between the canister and the LDP. If yours looks like this you may just have a clogged cylindrical filter. The filter isn't supposed to be serviceable but you can cut it open, clean the filter with carburetor cleaner and reseal it. Worth a try before you replace the whole assembly.

Good luck!

[jayiszraw]

not sure what i'm looking at.

[Bsix3.0]

same thing had been happening to my friend in his explorer. so this past weekend we took apart the gas tank filler hose and found it was full of multi vitamins! he had been having the issue for a few months so we decided to tear into it. suprisingly enough, multivitamins dont dissolve in gasoline. crazy shit..

we think it was our ex roomate, paul smola, so if you know him, kill him lol

[iamshayan]

underneath the back bumper under the spare tire well you will see this

in side you will be lookin at number 1 in the diagram (also pictured above) the big thing charcol canister evap canister vapor canister whatever you wana call it bottom line is that, gas vape runs through it on the two lines(28), and vapors go out the hose (18-35)to the LDP(5)............. i thiiink im not really sure how it works. ask old guy.

[old guy]

not sure what i'm looking at.

Look at the cylindrical object on the right side of the canister pic that i posted. It's in the line going to the LDP. Not all canisters have that filter. I believe it was used primarily in the European models. If you don't have that filter it would be replaced with hose #35 in the diagram that iamshayan posted. If you do have that filter you can cut it open and clean it out or just replace it with a section of hose if it is clogged.

[FoRbAnNa]

Look at the cylindrical object on the right side of the canister pic that i posted. It's in the line going to the LDP. Not all canisters have that filter. I believe it was used primarily in the European models. If you don't have that filter it would be replaced with hose #35 in the diagram that iamshayan posted. If you do have that filter you can cut it open and clean it out or just replace it with a section of hose if it is clogged.

I'm also having this issue with my car. I've had it since I bought it almost 3 years ago. I've never heard a "pssssssh" sound but everytime I fill up the tank no mather if its summer or winter or the tank is almost empty or 3/4 I can never fill it up without at least 3-4 shutoffs from the pump. It's impossible to fill the tank with the pump nozzle all the way in the filler tube, then it shuts off immediately so I have to lerk it out and try to fill with a lower pressure on the pump. After reading this thread and the other one you linked to this sounds like my canister or LDP. But there is no round plastic cover underneath my spare tire cavity as you described, It doesn't look at all like the pic iamshayan posted. I have a picture I took when I removed the round cover inside the trunk, could this be where my canister and LDP are? Mine is a european 2001 B6 A4.


The spare tire cavity is seen in the right top corner. Picture taken when the rear seats were down.

[my1stturbo]

IIRC from doing this on my Passat it's under the car, not from inside the trunk.

[old guy]

But there is no round plastic cover underneath my spare tire cavity as you described, It doesn't look at all like the pic iamshayan posted. I have a picture I took when I removed the round cover inside the trunk, could this be where my canister and LDP are? Mine is a european 2001 B6 A4.

The cover is accessed from underneath the car, not underneath the spare tire.

[FoRbAnNa]

The cover is accessed from underneath the car, not underneath the spare tire.

Do you have a pic for reference? I can't seem to find it. Also, the LDP vents to the left rear wheel well, right? Like in this pic? There isnt anything like that in my rear left wheel well.. There aren't any hoses at all actually unless you count the brakeline.. The charcoal canister in the front right wheel well that is connected to the fuel lines, is that something US cars also have or is my evap charcoal canister there instead of being in the rear? Have in mind that mine is a 2001 B6, the first model year B6 in europe and it could be that somethings are different on mine than later model years.

[old guy]

See the large round cover held on with three nuts setting directly between the mufflers? Your evap canister should be underneath that cover.



You will have to remove the left rear wheel well liner to see the LDP.

[FoRbAnNa]

OP, sorry for the thread jack but I also got the same problem.

Old Guy, my car doesn't look like that underneath or in the wheel well, look here:


Before I did the rust treatment I popped the three plastic plugs and with those gone I could see straight thru the car when I removed the trunk carpet and the spare wheel.

left rear wheel well




I've checked the part number on the black box thats hanging on the white rope, 8E0201803M. The name on the part on ECS is evapcanist and it says its for european cars. It's connected to the fuel lines so I would assume thats my evap charcoal canister, right?

[old guy]

That would be your evap canister. I have never seen one like that, so apparently some of the early European B6 models are totally different than the US and later European models. Do you know if you have an N80 evap purge valve located in the evap line above the air-box?

Edit: Looking at your evap canister I can see two lines. I assume the small line is the vent coming from the gas tank. The larger one appears to run toward the motor, so I assume that one goes to an evap control valve. Then there is something else showing between the two lines. Does that have an electrical harness attached? If so, I would assume that it is a vent valve that should open when the car is turned off. If it isn't functioning properly you would probably have trouble filling your gas tank.

One other thing to check. How heavy is the canister? It could be saturated with gas and consequently not functioning properly.

Try this: disconnect the small line connecting the tank to the canister the next time you fill up. If the problem goes away either the canister is clogged or the vent isn't functioning properly.

Good luck!

[FoRbAnNa]

Yeah I know this first model year B6 har some differences other than the charcoal filter too, like the fueling system is not the same as any later B6 model. They used the B5 fueling system as far as I know, a tuner told me that. A 2002 model tune or any other later model year won't work. After looking at B5s in ETKA I found out that they use the same type of charcoal filter in the same location as on my B6.

The canister has 3 lines connected to it, two small and one big. The first small hose is comming from the back of the car and is plugged in on top of the canister as you said, the other one is just a straight line from the bottom of the canister and exits at the bottom of the wheel well (venting?). The big hose runs from the top of the canister and in to a valve on top of the air box, a black valve that has an electrical harness connected. The valve makes a ticking noise when the car is running, is that normal? Is that my N80 valve on top of my airbox? By the way the charcoal canister does not have any electrical connections and the little white round thing on top of it in my last picture is just some kind of a vent I masked of with masking tape since I were sandblasting and didn't want sand to get in the filter.

In order to get to the filter I need to jack up the car and remove the inner fender liner and screw down the filter, I'll do that the next time I visit my parents house since they have a garage If I'm still having the same problem with filling the tank after disconnecting the small line on top of the canister, what else can I do?


Here is the ETKA drawing of the filter, is the valve with the number 10 on it the N80 valve you talked about thats sitting ontop of the air box? The parts with number 13 and 14 does not exist on my car.

[old guy]

#10 in the ETKA drawing would be your N80 purge valve, and yes it should make a ticking noise when the car is running. If you disconnect the line coming from the tank and it fixes your filling problem that would be an indication that a vent somewhere isn't opening when it should. Or it could be a saturated canister. You mentioned that there was a vent on top of the canister. That may be a one way valve that lets pressure escape but closes when the N80 starts purging the canister. Take a close look at that valve and see if it is operational. You might also want to post in the B5 forum since you mentioned that the canister looked the same as found in a B5.

Good luck!

[my1stturbo]

Just had this happen to me this morning. Went to fill up the tank and I could pump maybe 5 seconds at a time; I had just under a 1/4 tank when I pulled up to station. Each time I stopped pumping and removed the handle I heard a rush of air and it seemed liked gas actually came back out of the fill pipe as I removed the handle.

I remember the last time I got gas when I went to remove the handle it wouldn't come out and I had to twist and turn and fight w/ it a little(I might be remembering wrong, but isn't there a black plastic cap that sits on top of the actual metal flap that seals when you remove the handle). I just went to check to see if I felt the switch w/ my finger and when I pushed the metal door back it seemed to have almost no resistance to it. I'm at work but I'm guessing I can just yank that plastic surround around the fuel fill when I get home and check for hoses?

I'll try to pull the cover under the car and disconnect hoses from canister as well to see if that helps.

[Scrwedtxboy31]

Subscribed. Had similar issues, went away after a few fill ups. Now my fuel reading will only read to 3/4 after filling the tank up.

[k4kwame]

This is the version of the canister I have in my car (picture below). old guy mentioned that the cylindrical filter isn't serviceable but I don't see it in the picture of a new canister from ecstuning. Does anyone know if the cylindrical part is included with Charcoal Canister ? Not 100% sure it's the canister causing my problem yet, as I need to go back and rule out the LDP.

old guy, would you recommend also trying to test the cylindrical part through process of elimination? I'm not sure I have adequate tools to cut it open with, so it might just make sense for me to replace the whole part on this 10-year old car. How did you open it?

Thanks

It's one of two things. It could be a clogged canister or a non-functional LDP valve. Are you getting any LDP codes? The next thing to try would be to hook the large line back up and the next time you go to fill the tank up disconnect the small line that goes from the canister to the LDP. If the problem returns, replace the canister. If the problem goes away with the small line disconnected it would indicate that the LDP isn't functioning properly. The pressure normally vents through the LDP paper filter located underneath the drivers side rear wheel well when you are filling the tank. So either the canister is clogged or the LDP won't let the canister vent.

Usually the problem is with a clogged canister. Some models also have a cylindrical filter between the canister and the LDP. If yours looks like this you may just have a clogged cylindrical filter. The filter isn't supposed to be serviceable but you can cut it open, clean the filter with carburetor cleaner and reseal it. Worth a try before you replace the whole assembly.

Good luck!

[old guy]

This is the version of the canister I have in my car (picture below). old guy mentioned that the cylindrical filter isn't serviceable but I don't see it in the picture of a new canister from ecstuning. Does anyone know if the cylindrical part is included with Charcoal Canister ? Not 100% sure it's the canister causing my problem yet, as I need to go back and rule out the LDP.

old guy, would you recommend also trying to test the cylindrical part through process of elimination? I'm not sure I have adequate tools to cut it open with, so it might just make sense for me to replace the whole part on this 10-year old car. How did you open it?

Thanks

As you already noted the first thing you should do is to eliminate the LDP as the possible cause. Steps are outlined here: Clicky click. If you have access to a low pressure air source there is another easier method that you can use to test without having to actually attempt filling the tank.

When the key is the off position the LDP is normally an open vent to atmosphere. Any pressure build up of gas fumes in the tank get scrubbed through the charcoal canister and exit through the LDP. You can test the function of this system by applying low pressure air to the vent line that connects to the N80 purge valve located above the air box. Pull the line from the tank side of the N80 and apply no more than 1½→2 psi to the line. You should be able to hear a light hissing sound from the drivers side rear wheel well where the LDP is venting the pressure.

If you do not hear any air escaping disconnect the line going from the canister to the LDP. If you now get air from the line the problem is the LDP. If you still don't get any air you will need to repeat the process by removing the cylindrical filter. If you now get air flow the cylindrical filter needs repair/replaced. If you still do not get any air flow the problem would be a clogged charcoal canister.

Good luck!

[k4kwame]

So it turns out it is the cylindrical filter that is clogged on my car. For those interested in cutting that part open, I found this site: Click. It's in Russian but the pictures speak 1000 English words.

Otherwise, this version of the charcoal canister with the cylindrical attachment has been made obsolete. Those two parts have been replaced by 8E0201801L: Click and 8E0201946H: Click. Essentially it's a new version of the charcoal canister and just a hose going to the LDP.