Ok... just to add another data point:

I have a 2002 Accent L Hatchback that had the classical slow fill problem. It won't accept more than 0.3 gallons of gas without halting the pump.

I decided to tackle the problem head-on. The previous owner told me he had disconnected one of the hoses at the canister to diagnose the problem but it had not improved anything, and after reading these posts I concluded "head-on" implied the valve at the gas tank.

Alas... after several hours taking the tank down I found out it wasn't really necessary to do so: there were absolutely no pellets on the valve on top of the tank. I also found out this car's system is different from what is depicted in the TSB mentioned in this thread. From the valve there's a hose going to a box on top of the tank, and from there there's another hose going to the canister (light green below). It had a few pellets, but I don't think it's anything relevant.

The problem -at least in my car- was 100% contained at the canister and the device right next to it (the "Diagnostic Module Tank Leakage", aka DMTL). What I found was:
- The small hose at the right of the diagram (red) was 100% clogged with charcoal. I mean a solid plug of charcoal, that took some effort to clear.
- The DMTL device comprises a solenoid-actuated valve and a small electrical pump. The valve was jammed with charcoal, preventing it from closing. I managed to clean it.
- The yellow hoses had some pellets, but I don't think it was too bad. Just clean them
- The dark green hose connects a thin tube that goes to the top of the filling tube to the small nipple at the canister. There were some pellets at the thin tube, but the real problem with this line lies at a 1" or so filter that goes inside the canister. The one on my car was clogged with caked charcoal dust (try blowing into it... chances are you won't be able to), so...
- I had to cut the canister around 1" or so from the larger end (blue line). I placed the canister on top of some newspaper to catch the pellets and cut it using a Japanese (thin, pull) saw. You'll get to a spring-loaded plate that is supposed to apply some pressure to the pellets (I assume to avoid them from shaking too much) as well. I removed the filter inside the 1" tube (pushing it from the outside), cleaned it and reinstalled it.
- I got some A/C vent filters I had at home and immersed a piece in gasoline to see if it melted. It didn't, so I cut three discs out of this material, put them inside the 1" tube and put a piece of glass-fiber screen door mesh held in place with the same piece of tube used to hold in place the filter, so the discs will not come out.
- Cut more of the A/C vent filters to fit the bottom of the canister (where the inlets and outlets are located), cutting a hole for the 1" tube to go thru. I put three layers of filters on each side, and smeared some epoxy around the perimeter to make sure there was no way for pellets to get around them.
- Finally, I poured the pellets back into the canister, put the plastic plate and springs back, and used epoxy plastic glue to re-seal the canister. When done, plug two of the three holes with your fingers and confirmed there were no leaks by blowing some air into the 3rd one.
- I put everything back together and went straight to the gas station. I filled the tank in two minutes or so

There you go.

 

This 4WD Santa Fe has the drive shaft blocking removal of the carbon canister. But you can loosen the two 14mm nuts on the bracket in the middle of the two part drive shaft next to the canister in order to get enough room. Then remove the 3 10mm nuts that hold the canister metal enclosure in place. Disconnect the 2 rubber hoses and the electrical connector. Then wiggle the box out from above the drive shaft. You can then try blowing throw the hose to see if it is blocked. In my case the filter (smaller external box attached to the larger charcoal box) was clogged. I took the filter to the Hyundai dealer and they ordered a new one. Now the tank fills up most of the time.

 

Would some kind soul please tell me how the charcoal filter comes out? Does it come out of the port that is in the trunk and under the passenger side back seat? I have a 2009 Hyundai Sonata and I see the filter is in a metal frame and held in by two bolts. My thought is the two metal holding clips on each side of the filter should be removed. *Maybe* the filter in its bottom metal holder slides forward and up and over the gas tank but maybe the gas line and float going into the tank has to be removed (four screws removed and float pulled out of tank) to give more room to get the filter assembly out? Everyone talks about getting the charcoal filter out and then doing ABC, XYZ, and such-and-such a thing but let's walk it back a step. Where is the charcoal filter going to be pulled out and how? Thanks!

 

Somebody can tell me, what happen if I purge ALL carbon of canister filter? It's dangerous?

 

Please clarify what you are trying to do. I don't understand:

 

Last friday, I unmount canister filter, and I found a lot of carbon ball (smaller), so I remove all carbon inside canister filter. The question is, it's dangerous? I solve the problem of slow fill

 

I checked the venting in our 2002 Accent, and I found that everything basically worked, except that there was charcoal in one of the rubber hoses near the canister. I went to a self-service wrecking yard (breakers for the U.K.) and I pulled out 5 canisters before I found one that did not have charcoal coming out of it. I checked all of the lines to make sure that they were clear. I installed the replacement canister, and the problem was solved. I decided to cut open the canister I removed, and it looked like pictures I had seen on the forum. It has 2 baffles, one at each end. It allows air and fumes to be spread over the entire surface of the charcoal. In the first picture, you can see where the thin foam filter has melted and partially blocked the baffle openings.

So there are 2 restrictions in the system. The foam is clogging the baffle, and the charcoal is clogging the vent line. I kept all of the charcoal in a plastic food bag. The end where the hoses connect has a baffle too with the same foam filter.

The flow seems to be down one side of the canister, under a divider, and up the other side. I am going to try to clean all of the foam out, use metal screen, and put the canister back together with epoxy. I let you know how it works.

I went to the Hyundai dealer, and asked about a new canister. They are $185 or so, which isn't too bad. The parts man said that he sells a lot of them (I'll bet!). I also replaced the fill shut off valve in the inlet of the tank, as our old one was a little sticky.

For those of you in the U.K. I understand that petrol stations had to buy smaller nozzles so that new Hyundai cars would not trip the automatic shut off on the nozzle. If you look under the car, the fill pipe is rather small compared to other cars.

I hope this helps. Hyundai needs to change how they build the canister.

 

When I went looking for charcoal canisters in the wrecking yard, they were all under the car, directly behind the left tire close to the filler. They are covered by a black plastic box that has some openings on the bottom (I guess to drain water that splashes up in there.). There are 3 screws (12mm? 8mm?) that hold it in. I looked at a few different models to see if I could use perhaps a larger canister for better flow, and that seems to be where they put the canister on all of them. You may also have to remove a plastic inner fender to access it.

A note: Hyundai uses some sort of sensor in the vent line. I wonder if it would trigger a fault code and turn on the check engine light if the carbon is dumped out of the canister?

 

You mean like this?


Those aren't carbon *****, they are charcoal pellets. Do you mean you gounf them in the canister or something else? They are supposed to be in there, they are part of the emissions system and removing them is illegal (in the US) because it defeates the purpose of the canister. If they were somether else then yes, removing tthem will solve the problem because they aren't supposed to be anywhere besides the canister itself.

 

Yes, it's like this... I live in Costa Rica, here's vehicle technical review, but the measures they are for emissions after catalyst (I think my "canister fix" its independent of this)....