Slow Fuel Fill Problem Diagnosis
Junior Member
Joined: Mar 2015
Posts: 5
Hi, very detailed information, thank you. However, where can I find the schematics to show me where they are located? I am having the same problem with my daughters 2004 Hyundai Accent. I had a mechanic put some parts on it, but don't remember which ones he replaced. I believe he put used parts on too. I would like to fix it myself to save a bunch of money on labor. Problem is, my daughter works an hour and a half from me so have very limited time to fix it. Thanks again .
Junior Member
Joined: Mar 2015
Posts: 5
gas filling problem.
I wanted to add my experience/fix here.
My mom's car (2000 Elantra, 195k miles) has had this problem for a few years now. For about a year, I'd been able to remove that line from the charcoal canister connected to the liquid vapor canister, dump all the pellets out, and allow her to fill-up relatively trouble-free. The pump would still shutoff every $5-6. These past 6-7 months though, it got to the point where it shut off literally every few seconds and made it absolutely impossible to fill the tank up, even with the line on the liquid vapor separator completely removed. The filler neck would spit gas out all over you and down the side of the car as well. When you can no longer fill-up even with the charcoal canister to liquid vapor separator hose removed, pellets have clogged the lines between the fill vent valve and the liquid vapor canister, and nothing you do on the charcoal canister side will fix the problem at this point.
It's obvious/already stated here the main culprit is the charcoal canister. We already know there is a "membrane" that bursts when gas gets into the canister and swells the pellets, allowing the pellets into the vent lines and clogging them up.
I wanted to see this "membrane" and find out exactly why it fails so I cut the charcoal canister apart to have a look-see. Here's what it looks like cut apart, about what we'd expect, just a container full of charcoal pellets. Interestingly there are two separate chambers for each line:
Because of the two chambers, I cut the top into two sections to be able to seal the chamber back before putting the top back on. Anyway, as you can see, here is our mythical "membrane" - just a friggin piece of thin foam. No wonder it fails! A really surprisingly terrible material choice by Hyundai. Of course we aren't SUPPOSED to overfill the tank, but surely Hyundai knew it would happen and should have used mesh instead:
You can see this side hasn't failed (yet), but is close to it:
So, my curiosity quenched, I permanently fixed the canister (the way Huundai should have built it in the first place) with mesh. I just used the mesh from cheapo mesh sink drains:
I used two part "plastic weld" to put it all back together (better than new):
Now, clearly you don't have to go through all this trouble. As somebody said already in the thread, you can just use mesh over the outside holes on the canister and achieve the same effect. Again, I just had to see the exact cause for my own curiosity.
Unfortunately, even after this, I still wasn't able to fill the tank up. I figured the line between the fill vent valve and the liquid vapor separator was full of pellets and perhaps even the fill vent valve itself had pellets. I dropped the tank, and sure enough I was right. Here's the fill vent valve, full of pellets, as you can see:
I didn't take a picture but the entire hose between the fill vent valve and liquid vapor separator was full of pellets too. Unfortunately there's no good way to completely clean out this line or the fill vent valve without dropping the tank, removing the line and the valve, and manually dumping the pellets out. I also removed the liquid vapor separator and by being ale to turn it all around in various directions managed to dump a whole bunch more pellets out of it (surprising, as I figured it would be empty from my dumping it and tapping on it all the time in the past).
I put it all back together, went to the station, and filled it right up completely and quickly. I am confident it's now permanently fixed.
It sucks I had to go through all this trouble due to Hyundai choosing to use foam instead of mesh. It only cost me about $10 total but dropping the tank definitely isn't fun and all in all this took me a good 4-5 hours of my time/labor (though granted some of that spent on cutting the canister up and repairing it, again you can just mesh the outside holes). I know, however, that my mom will appreciate the permanent and complete fix. Good luck to the rest of you guys out there with this issue.
My mom's car (2000 Elantra, 195k miles) has had this problem for a few years now. For about a year, I'd been able to remove that line from the charcoal canister connected to the liquid vapor canister, dump all the pellets out, and allow her to fill-up relatively trouble-free. The pump would still shutoff every $5-6. These past 6-7 months though, it got to the point where it shut off literally every few seconds and made it absolutely impossible to fill the tank up, even with the line on the liquid vapor separator completely removed. The filler neck would spit gas out all over you and down the side of the car as well. When you can no longer fill-up even with the charcoal canister to liquid vapor separator hose removed, pellets have clogged the lines between the fill vent valve and the liquid vapor canister, and nothing you do on the charcoal canister side will fix the problem at this point.
It's obvious/already stated here the main culprit is the charcoal canister. We already know there is a "membrane" that bursts when gas gets into the canister and swells the pellets, allowing the pellets into the vent lines and clogging them up.
I wanted to see this "membrane" and find out exactly why it fails so I cut the charcoal canister apart to have a look-see. Here's what it looks like cut apart, about what we'd expect, just a container full of charcoal pellets. Interestingly there are two separate chambers for each line:
Because of the two chambers, I cut the top into two sections to be able to seal the chamber back before putting the top back on. Anyway, as you can see, here is our mythical "membrane" - just a friggin piece of thin foam. No wonder it fails! A really surprisingly terrible material choice by Hyundai. Of course we aren't SUPPOSED to overfill the tank, but surely Hyundai knew it would happen and should have used mesh instead:
You can see this side hasn't failed (yet), but is close to it:
So, my curiosity quenched, I permanently fixed the canister (the way Huundai should have built it in the first place) with mesh. I just used the mesh from cheapo mesh sink drains:
I used two part "plastic weld" to put it all back together (better than new):
Now, clearly you don't have to go through all this trouble. As somebody said already in the thread, you can just use mesh over the outside holes on the canister and achieve the same effect. Again, I just had to see the exact cause for my own curiosity.
Unfortunately, even after this, I still wasn't able to fill the tank up. I figured the line between the fill vent valve and the liquid vapor separator was full of pellets and perhaps even the fill vent valve itself had pellets. I dropped the tank, and sure enough I was right. Here's the fill vent valve, full of pellets, as you can see:
I didn't take a picture but the entire hose between the fill vent valve and liquid vapor separator was full of pellets too. Unfortunately there's no good way to completely clean out this line or the fill vent valve without dropping the tank, removing the line and the valve, and manually dumping the pellets out. I also removed the liquid vapor separator and by being ale to turn it all around in various directions managed to dump a whole bunch more pellets out of it (surprising, as I figured it would be empty from my dumping it and tapping on it all the time in the past).
I put it all back together, went to the station, and filled it right up completely and quickly. I am confident it's now permanently fixed.
It sucks I had to go through all this trouble due to Hyundai choosing to use foam instead of mesh. It only cost me about $10 total but dropping the tank definitely isn't fun and all in all this took me a good 4-5 hours of my time/labor (though granted some of that spent on cutting the canister up and repairing it, again you can just mesh the outside holes). I know, however, that my mom will appreciate the permanent and complete fix. Good luck to the rest of you guys out there with this issue.
Member
Joined: Jun 2013
Posts: 30
Skeeder1964: The charcoal canister is between the right rear bumper and the right rear tire. It is covered by a piece of black plastic. If there is an electronic detector in your model, it will be there. The vapor separator is attached to the fill pipe, connected by black hose. The vapor connection to the gas tank is on top of the tank, near the fuel pump. There is an access panel to the fuel pump in the car. It is just glued on, so pry it off, and disconnect the hoses and electrical connections to the pump there. You then have to remove the gas tank to get to the vapor vent connection. Clean out everything associated with vapor. Cut the charcoal canister open a little below where the hose connections are. I used a reciprocating saw. Replace that cheap, junky, foam with window screen. I think that steel should be OK, because there is no water in there to rust it, but just to be sure, I'm going to use stainless steel or brass. I'm going to epoxy it in there, and epoxy the canister back together. The last time I had my gas tank out, I also replaced the check valve that is in the tank at the base of the fill neck. It made a difference when filling the car. It was only about $7 at the dealer. I put a used canister that did not have charcoal falling out of it when I held it with the hose connections pointing down and shook it. I had to check 6 of them before I found one that passed the test. This gave me time to modify the one in the car. At the dealer, the price of a new canister for our 2001 Accent was $189. Hope that helps.
Junior Member
Joined: Aug 2014
Posts: 13
Does anyone know how the carbon canister is changed on a 2009 hyundai sonata? It is above the gas tank. I have some access through the trunk through a removable panel. However, I think the tank has to be dropped. Anyone? Help would be appreciated.
Junior Member
Joined: Mar 2015
Posts: 5
Okay thank you. I will give it a try. My gas tank filler is on the left side of the car though. So I see where it is though. Next time my daughter has time to come home I will take a look at it. Thank you for your comment.