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Slow Fuel Fill Problem Diagnosis

  #141  
Old 01-12-2018, 05:03 PM
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Join Date: Jun 2013
Posts: 28
Default Inside the canister

I looked at the one I have, and at photos of another one that I has cut apart maybe 2 years ago. I'll call the end with the connections the top. There is a pipe from the purge connector to the charcoal. If you want to avoid cutting that, cut about 2 inches below the top where the 2 hose connections are. You could cut the bottom where it is sealed. I looked at the top and bottom and there are separator plates. The bottom one has several holes drilled in it, and the top has fewer large ones. The foam separators are on these plates, facing towards the charcoal granules. My guess is that this foam is plugged or melted. Some people have removed the foam and replaced it with brass or stainless steel screen. When you cut it open, you will want to have it over something to catch the charcoal. A good epoxy should work well to assemble it. I don't think that you need to cut the top in half like I did.


Cut about 1" lower than I did.



The bottom separator with some of the foam on it.



Top separator, had foam on it. Pipe on left is below the purge hose connection on the outside. It has a piece of fabric in it
 

Last edited by GaryL; 01-12-2018 at 05:05 PM.
  #142  
Old 01-13-2018, 05:13 AM
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I would keep an eye on the air filter tube that in in the middle of the gas neck hose to the carbon filter. I have found it holds very fine carbon dust. Take it out, tap it, blow it out to hell and back, and it still can be a part that is shot, over the hill. It can bottleneck the air to and from the charcoal canister. So if the gas is spitting back out, try taking the air tube filter out and bypassing it with a small piece of copper pipe to test if gas now enters the tank freely or not. And if you do have charcoal bits in the line, then yes...the charcoal canister has to come out and be replaced or cut open and fixed. Just the charcoal canister, new, and the air tube filter, new, are retail close to $800. Some sites sell cheaper. So the up front legwork and experimentation and fixing of existing parts=savings. This fuel thing is a regular occurence every 30-40,000 mph or 48,000 k to 63,000 k. So getting a handle on all this is a money saver. Also, thanks to all who posted before and helped me help myself with this fuel problem.
 
  #143  
Old 11-06-2018, 04:28 AM
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You got it.
 
  #144  
Old 11-06-2018, 02:22 PM
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This is helpful, thanks! I was able to get the charcoal canister in like new condition on EBay for just $80.
 
  #145  
Old 11-21-2018, 09:57 PM
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Join Date: Jul 2018
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this is my first post on this thread. i have been struggling with an 09 sonata 2.4L slow fuel fill and MIL lamp on/off issue for a number of months and miles. i spent a lot of time reading threads on this and other sites. i took the easy road and have replaced the canister vent valve, the fuel pump assembly [which includes the fuel tank pressure sensor] and now the charcoal canister [which i purchased from autozone for about $100 and has a hyundai logo on it]. unfortunately, the old canister [original as far as i know, with 106KMiles] appeared to be in perfect condition. no bits and pieces in any of the 3 attached lines, and air flows as freely though it as it does with the new replacement canister, with very little back pressure. i also removed the canister inline air vent filter, and while i can blow through it in both directions, there is substantial back pressure, but i have nothing to compare with. i plan to follow the suggestion of an earlier post and temporarily substitute a piece of 1/2" copper pipe and see what happens.

i did check the fuel tank vent line and it appears to be working as expected, allows air to exit the tank and not flow into the tank. likewise, the fuel tank filler port allows air [and hopefully fuel] to flow into the tank and not out of. the tank "recirculation" port allows air to flow into the tank [with some back pressure], but not out. i assume this the normal.

as for exchanging the canister, i was able to remove the two rear fuel tank strap attachments while supporting the tank with a jack [car up on jack stands also], and lower the rear of the tank enough to get the canister assembly out of its location above the cross member. note that i minimized the weight of the tank by using up most of the fuel. lowering the rear of the tank also gave easier access to the two canister assembly frame mounting bolts as well as the fuel fill hose clamp on the tank. the fuel fill hose had to be removed before the tank could be lowered enough for the canister assembly to exit between the tank and the cross member. having not worked with the quick-connect connectors used on various lines, it took me some time to figure out how to get my fingers around them to press the release on both sides simultaneously. another case where having the rear of the fuel tank lowered help for access.

i will put all things back together in two days, make the copper pipe substitution, and report the results here.
 
  #146  
Old 11-22-2018, 10:04 AM
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Well thank you for explaining how to lower the tank. I never figured that out. Remember, if you jack up your rear left side, take off the tire, and remove the well cover, you get to one solenoid. This is in case you have to move past the copper pipe thing (you still have trouble with filling gas). I changed mine just because of because, and the one under the hood on the slightly to the right center of the engine front. The air filter for the gas tank...you really can't blow it out and make it work for very long. So if your canister is fine, and you remove the air filter...and you are successful, great. If not, change the two solenoids to make life easier on yourself. I think Advance or Autozone has the solenoids...modestly priced. Once you reach the point of where it is easy to fill the tank, you are done. I think the solenoid(s) give(s) up the ghost too and when I did mine, I just wanted to get it working and be done. The front solenoid is easy enough to do. The one under the left wheel well cover is easy enough but a bit more of a nuisance. I have changed mine 2x is 242,000 miles. However, the dealer did two under warranty. If you have 106,000 miles on yours, count yourself lucky you did not have to change anything 50,000 miles ago.. It seems every 45-50 k the fuel fill problem comes back.
 

Last edited by dkodgis; 11-22-2018 at 10:27 AM.
  #147  
Old 11-22-2018, 01:34 PM
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Motretu: With back pressure in the air filter I would replace it anyway, and if I were betting on it, I'd say that it is the problem. I cut mine open with a reciprocating saw and found 2 problems. The first problem is that the filter is just 4 pieces of filter paper, and the part of the filter that is exposed to the atmosphere was clogged with dust. Makes sense that it would be clogged, since it is just behind the rear tire on my 2002 Accent, and San Diego can be a dusty area. The other problem is that the filter paper exposed to the atmosphere is much smaller than the piece that is behind it, so it clogs up quickly- Stupid design!! MacGyver would be proud of my solution. Dacron fill for upholstery does not dissolve in gasoline (I tried it). It looks like raw cotton before it is spun into thread. I put some in the filter housing, glued the housing back together, and reinstalled it. We have not had any problems filling the tank for about 4 years now. If you look at much earlier posts, in Great Britain I think that it was BP that changed all of their fill nozzles on their pumps to a smaller size so that people could fill their Hyundais. Hyundais have a small diameter tube to the tank, so that when the tank is being filled, there is very little room for vapor to escape. That creates back pressure which trips the fill nozzle shut off. Sometimes there has been a problem of the incoming gasoline completely blocks off the fill tube in the car, pressure builds up in the tank, and when the fill nozzle shuts off, a lot of gasoline will blow back out of the fill pipe.
 
  #148  
Old 11-22-2018, 05:19 PM
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update on my post, this thread, of 11/21/2018 re 09sonata 2.4L slow fuel fill and MIL indicator.
put all parts back [did not have any left over] with the canister air vent filter replaced by a tube. took car to local fuel station [which had issues filling in the past] and tank filled 15gals without issue, with nozzle inserted normally. so i'm inclined to believe that the canister air vent filter being partially plugged was the issue [given that the original canister, which was replaced cause i had a new one, showed no signs of failure]. have not gone the next step to replace or modify the canister vent filter. according to my partner of the last 2 yrs, who owns the car and has driven it since new, the slow fill issue has been around for at least 20k miles, but has been manageable until recently. the car has been to several repair shops for the slow fill and MIL issues, including a smog test. each time, the car has been returned with the MIL lamp off, and a pass on the smog test. but in all cases, the MIL came on with in 1k miles or so, and the slow fill issue was not corrected. the jury is still out on the MIL issue, as the indicator had gone off by itself [common behavior] before i started the current project.

clearly it would have been much easier to have done the canister air filter trick first, but i did not find this thread till recently, and i had already purchased a new canister [and did not realize the level of difficulty replacing the canister], and had already replaced the fuel cap and canister vent close valve.
 
  #149  
Old 11-23-2018, 07:49 PM
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update 2 on my post, this thread, of 11/21/2018 re 09sonata 2.4L slow fuel fill and MIL indicator

hyndai calls the unit we've been referring to as a "canister filter" by a different name, "auxiliary vapor canister" pn 314210A000. a local san diego dealer sells it for $201, but i found it on amazon for $161 and ebay for $121. according to the SD dealer, the real canister vent "air filter" is integrated with the canister vent close valve and that's consistent with my searches. so it is not clear what the "auxiliary vapor canister" is intended to do. i did find a claim the the unit contains additional charcoal, but that is not consistent with what was reported in this thread..

i have not taken my unit apart yet, but one poster in this thread reported an interior series of elements that look like filters rather than charcoal elements. so i'm confused and will need to take mine apart to clarify.
 
  #150  
Old 11-24-2018, 08:30 AM
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Between one of the fuel fill neck hoses and the charcoal canister is a cylinder air filter. That is what I removed and used the copper pipe for. When I got under the car and removed one hose off of the cylinder air filter, and the other end of a hose also connected to the charcoal canister, the result was there were two rubber hoses coming off of the charcoal canister...so I could see a) if there were charcoal pellets showing up out of the hoses when I freed up the hose ends , and b) if air was flowing through one hose end it when I blew on the other end of the hose. In my case, I saw no pellets and I saw none exit the charcoal canister when blowing through either hose so I thought my charcoal canister was fine. I did not want to drop it and change it and until a few posts ago when someone said to lower the tank, I did not even know how to change it.

I concentrated on changing the fuel tank fill neck solenoid. If memory serves, that was about $24. The other solenoid under the hood was a bit more but I did both in case the back pressure had somehow damaged them. I was not going to test them with a meter to see if voltage was there and I could not find specs. So for me, the two solenoids and the substitution of the 1/2 inch size and six inches in length copper pipe worked in place of the gas tank air filter in the form of a cylinder. Everything was fairly easy.

Of course if you suspect your charcoal canister and/or if you see charcoal pellets, then change it. The only air filter for the gas tank is the cylinder-shaped one in-line between one of the hoses coming off the filler neck and going to the air filter cylinder, and coming out of the air filter and over to one of the ports on the charcoal canister. Everything is easy enough to do except the charcoal canister.

As an aside, when I had the car from new until 46,000 miles, the fuel thing kicked in. I took it to the dealer, and they fixed it (changed the two solenoids, and air filter cylinder). However, in a week the light came back on. I took it back to the dealer and they changed the charcoal canister. I have to think they thought it was OK because of no loose pellets but in that case, I guess it was not. I still have the same charcoal canister 200,000 miles later. What drove me to simple? The last two times, I never knew how to change the charcoal canister and the dealer would not tell me. However, the two times I changed the solenoids and the second time I took out the air filter cylinder after 190,000 miles, all worked. One other tip, if you are not in a hurry, is to leave the two hoses connected to the charcoal canister and loose/not connected on the other end for a day or two so vapor escapes (obviously, do not drive the car unless everything is back, connected). If you really need to change the charcoal canister, and the solenoids, and the air filter, it turns into a pretty penny. So I kept my charcoal canister which all indications pointed to its working, and ditched the air filter cylinder for the gas tank, and did the easy, less expensive solenoids. The charcoal canister would have been the only thing left. So I did not have to bite the bullet and go for the canister.

At each step, but with everything reconnected, have a small gas can ready to try to fill the tank. If the gas goes in easy, you are done. If not, you have to continue and decide what steps you want to tackle or need to tackle where there is obvious physical damage. I tried to blow out the air cylinder filter for five days with a monster compressor. It worked for a day or two and the light came on. In other words, the air filter needs to be replaced or removed. It saves money and my car has passed inspection every time. In all, I have had the fuel thing four times. Dealer=one fix. Me=three fixes. If I had to swap out the air and charcoal things, it would be a hit on the wallet. First I work simple until I have to open my wallet. Hyundai knows this fuel thing happens. I guess it is a money maker for them
 

Last edited by dkodgis; 11-24-2018 at 08:39 AM.
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