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I have the issue where I can only fill a few seconds before the gas station pumps "trip" and stop fuel flow. I'm in California and I don't know if this applies to all states but here they are pretty aggressive about updating the nozzle and vapor capture design so vapors are not released while filling. This makes for a very unpleasant and long filling process if your system is clogged like mine.
After seeing this thread come to life I am inspired to take on the project and I won't be paying the dealer to do the labor. I will take pics and post them.
More to follow. Thanks to all previous contributors.
For now, in case it helps anyone here's a PDF showing the components involved for my particular 2007.
Any luck or other options with this? I bought a 2007 S550 and am having this issue. Bought the car with the tank full... Have had 2 long and painful fill ups and figured there is an issue. Private party buy so I f'd myself there... Any DIY links or part needed or are we looking at an $800-1000 bill regardless?
OK, my turn to deal with charcoal canister issue. Getting in to the point that I can’t fill gas and the nozzle popped up in every few seconds.
The canister and valve are low tech stuff and how complicated it can be? Decided to check it out.
Took it off (procedures can be found in the forum) and separated shutoff valve from charcoal canister. There are a lot dust between charcoal canister and valve. Opened up the valve, very simple stuff with an electric solenoid and a spring. There is a lot of dusts/debris in the valve too. Cleaned them all up. Using air to blow charcoal canister and felt low resistance, which is good. Shacking the canister and heard charcoal move sound so charcoal is not tarred up.
Next step (you may skip this step as I still think dusts/debris was the cause), put the charcoal canister in oven, set to 280F for 1 hr. ***Be careful to make sure no gasoline is trapped in the container or the thing can catch on fire. *** Increased temperature gradually to 280F. A lot of water steam came out at first 20min, some gas smell, not too bad. Don’t think this way to re-activated charcoal but just to dry it up. To make activated charcoal one needs 1700F in a closed container.
Then put back and all look good.
Went to the same gas station twice and no issue so far.
Also, notice that I am getting 26mpg on the same road trip again. Was 26mpg sometime ago but recently only got 22-23 mpg on the same road trip. So guessing this is part of EMISSION control system and can impact mpg in some way.
Thought to share if you like to play tools. This is a small project and took 2 hours.
correction: 280F
2 months after cleanup, no problem to fill up gas at all.
OK, my turn to deal with charcoal canister issue. Getting in to the point that I can’t fill gas and the nozzle popped up in every few seconds.
The canister and valve are low tech stuff and how complicated it can be? Decided to check it out.
Took it off (procedures can be found in the forum) and separated shutoff valve from charcoal canister. There are a lot dust between charcoal canister and valve. Opened up the valve, very simple stuff with an electric solenoid and a spring. There is a lot of dusts/debris in the valve too. Cleaned them all up. Using air to blow charcoal canister and felt low resistance, which is good. Shacking the canister and heard charcoal move sound so charcoal is not tarred up.
Next step (you may skip this step as I still think dusts/debris was the cause), put the charcoal canister in oven, set to 280F for 1 hr. ***Be careful to make sure no gasoline is trapped in the container or the thing can catch on fire. *** Increased temperature gradually to 280F. A lot of water steam came out at first 20min, some gas smell, not too bad. Don’t think this way to re-activated charcoal but just to dry it up. To make activated charcoal one needs 1700F in a closed container.
Then put back and all look good.
Went to the same gas station twice and no issue so far.
Also, notice that I am getting 26mpg on the same road trip again. Was 26mpg sometime ago but recently only got 2-23 mpg on the same road trip. So guessing this is part of EMISSION control system and can impact mpg in some way.
Thought to share if you like to play tools. This is a small project and took 2 hours.
correction: 280F
2 months after cleanup, no problem to fill up gas at all.
the failure described in this thread is caused usually mostly by topping off the tank after the initial shut off.
never top off. or you will drown the charcoal and you will need to dry it manually (in an oven as mentioned above)
never top off my car. It's the design of the valve that open to env. and can trap dirt. They have newer parts. Either way, cleanup instead of replacing .
The charcoal units on the original W221's were a faulty design. There is an updated design that cures the problem.
Note that when you order the new tank, there is an adapter wire that needs to be ordered too. It connects between the existing car harness and the new tank. I think the new tank is from a different model, so it has a different connector.
I bought a used "new style" tank and the adapter cable. Tank didn't work.. pulled it off and found it had a crack in it. Kept driving it for 4 weeks because I didn't have time to fix the car.
I then reinstalled the original tank (which had been drying out in the garage for a month) and it worked fine. That was last Jan and it has now been almost a year on the original tank and it's working fine.
I would suggest pulling the tank, keep driving the car, then put it back in a few weeks later. If you can put it in hot sun, great. Do NOT put it in the oven!!! Think carefully about why you don't want to put a mostly sealed tank full of gas and gas fumes into an oven and bake it (ie: BOOM!)
Disconnecting the hose won't work.. you'll get a check engine light since the system detects an evap leak. Best you can do is disconnect, dry it out, then put it back in.
If I had to do it again, it would probably make sense to stick a small fan on the intake port (maybe tape a funnel on the fan) and let air blow through it for a week or so. I wouldn't use a hair dryer due to the gas.
Thanks to all who have posting on this subject and for the great info on this problem. I've been dealing with this for some time now with my 2007 S550 and it was starting to get tiring.
I took the filter assembly off this afternoon and found an incredible amount of dirt clogging the filter for the solenoid. I blew everything off and also washed the foam filter and let it dry. I put it all back together and filled the tank. No problem filling with the hose on the highest setting. That's the first time I've ever been able to do that since I bought the car. (It now has 96k on it and I bought it with 81K)
The entire job took less than an hour deducting for the time to dry the foam filter. Easy job - I don't see how the dealers can justify what they're charging for this. All you need is a 10mm socket, a small screwdriver (to pry the two plastic pins up that hold the fender well liner) and a pair of plyers to remove the lower charcoal filter hose. The upper hose can be removed with your fingers by pressing in the two releases and simply pulling it up and off.
It's a dirty job but it's only dust you'll get all over yourself, no oil or grease. The hard part is getting the fender liner off and back on again.
Last edited by donnelsen; Sep 28, 2019 at 11:06 PM.
Does this fix also helps with a diesel engine? I have a 350 '12 diesel and have the same problem. Fills up nice with the regular speed but when i use the semi-truck nozzle it shuts of immediately.
Does this fix also helps with a diesel engine? I have a 350 '12 diesel and have the same problem. Fills up nice with the regular speed but when i use the semi-truck nozzle it shuts of immediately.
I am surprised you can get that nozzle in the filler. I am pretty sure that the volume of the commercial truck nozzle is too much for the car to handle at once. My trucks have 45 gallon and 75-gallon tanks, From near empty, they can take a full load of fuel on in roughly 5-6 minutes. It takes me longer to pay with a T-Chek card than it does to fill up.
What i meant was that whith certain gas-fillers you can push a button here in the EU wich actuates a more heavy flow of diesel. The nozzle is the same as any other. Just push the button on the fillerstation. You can fill your 70l tank within 1 min. In all my other MB's it wasnt a problem, but just now on my W221 350CDI it seems the same problem as the OP gas equivalent. My first gues was maybe a faillure in the tankevaporation/tankventing system, until i came by this post.
Just filled up after cleaning the canister filter under the solenoid with plain soap and water—this actually works!!
This thread references the 550 but on my 600 the process seems to be surprisingly less complicated.
On the 600 you’re removing 3(10mm) screws to release canister from the body of the car and it’s completely unnecessary to unclamp the bottom hose.
Those factory clamps are a headache and can easily make this job more time consuming than it needs to be.
Once you remove the 3 screws, the main breather hose on top the canister is a simple squeeze tab and pull up.
When the top hose is removed the electrical connector to the solenoid is a simple squeeze clip and once disconnected the canister can be moved freely pretty much
(STILL TAKE YOUR TIME AND MOVE CAREFULLY)
I turned the canister completely upside down to clean with no issue—
**BE SURE TO PUT THE O-Ring back after cleaning because you will get a P0455 code🤣🤣🤣 ask me how I know this*
This is after shaking out a lot of dirt and first wiping down was much dirtier then I decided to take pics so this is not even as dirty as it was upon first opening. Cleaned with dish soap and water. Kept the opening downward and sprayed soapy water upward to ensure water was never able to settle in the filter housing. Used an old dish soap bottle to squeeze soapy water upwards and had a separate clean fresh water bottle to remove soapy water while gently scrubbing with a clean rag. Filter started off completely soiled and dirty this is after.
I would have loved to have some pressurized air but no access—so I simply found an old baby nose suction and cut the tip diagonally to create a angled surface to improve suction which was more than enough to PULL THE DIRT OUT—intuitively this seemed like a good idea lol Used to suction moisture out of filter primarily and once visibly dry I also used it to blow air over filter. I also turned canister upside down and suctioned the main hose opening just in case there was any debris that was there after gravity did most of the work.
Finally, I spayed the solenoid down with mass airflow sensor cleaner.
i sprayed through the opening on the solenoid neck until the spray was clear coming out the bottom and then I sprayed from the bottom afterwards til the cleaner flowed through the opening.
Currently I drive: 2007 S550, 2009 ML350 and 2004 CLK320.
Thank you for all your inputs!
This weekend I have removed the vapor canister, separated the valve. Then simply vacuumed the valve and all openings in the canister. Put everything back. And... It worked!!! I filled the full tank at California Costco without false-triggering the shut-off valve.
This weekend I have removed the vapor canister, separated the valve. Then simply vacuumed the valve and all openings in the canister. Put everything back. And... It worked!!! I filled the full tank at California Costco without false-triggering the shut-off valve.
The current mileage is 173500 miles.
After 3+ years of assuming my slow gas fill-ups were due to a design flaw, I came across this thread. I did the same fix. After removing the solenoid valve, I saw that the flat filter below it (going into the charcoal canister) was completely blocked. Using compressed air, I cleaned the flat filter, the valve itself, and the foam sleeve that goes on the valve. I headed straight to the same gas pump I always use....and voila! Pump did not "false click off" a single time. First easy fill-up in years.
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Think carefully about why you don't want to put a mostly sealed tank full of gas and gas fumes into an oven and bake it (ie: BOOM!)
