My 430 won't let me put any gas in it.

I can get about one squeeze in before the nozzle sensor shuts it off. Doesn't matter how I position the nozzle or how slowly I try to fill it. It stops almost instantly. Sometimes there is a backflow which spills gas on the car and ground. Also it doesn't seem to be temperature dependent because I have tried to fill up in the bitter cold and when it had warmed up considerbly. I have also been to many different gas stations too.

Any help would be greatly appreciated.

Thanks

 

Please, everyone, when you start a thread, the title should be a description of the issue. I get IM’s and emails all the time asking me questions that I know I’ve read about, but the thread titles give no indication as to the problem being covered. The title of this thread is “Please Help!” I’m from NYC where “Please Help” is the universal sign for people to mind their own business and keep walking. No, it’s not humane, but that’s what we do because there’s no sense in both of us getting robbed. “I need help putting fuel in my car” is a much better title.

Here is what I think the problem is: When you add gasoline to your tank, air is displaced using vent lines. Your tank isn’t venting. The W208 has a saddleback gas tank with two vent lines. Those two lines go to a charcoal canister, and from the canister out to another line which feeds a valve, and so on. The canister is clogged. Why is the canister clogged? [caution: run on sentence alert] If gasoline gets into the canister, say by someone overfilling the gas tank, the charcoal will break down, clog the system, and very little, if any, air will be able to pass through. If air can’t leave the gas tank, gas won’t go in. The canister will also clog due to old age because gas fumes will break down charcoal too.

Your vent system looks like this
Gas tank - - - - - - 2 vent lines - - - - - > charcoal canister - - -1 vent line - - - >

The good news is – if you’re handy, the workaround is less than $10. If you take it to a dealer, the factory fix will cost several hundred. The middle of the road fix is for you to make your own (air tight) canister. That can be done for under $100.

I don’t think anyone is going to pay a dealer for a new canister, and the very few who are going to build their own can figure that out without any help, so I’ll tell you how to bypass the system.

Remove the driver’s side rear wheel, then remove the plastic inner cover, and look up. That’s the charcoal canister. Remove the two lines going in, and the one line going out. At this point you could remove the old canister and install a new one . . . . . . or you could measure the lines to see what sized tee you’ll need for the $10 workaround. Alternatively, you could buy a $4 Dorman Help tee, part number 47112. It’s sold at just about every automotive chain store under the sun, and is a 3/4 by 3/4 by 3/8 tee. Buy some hose clamps, some (quality) hose, and bypass the canister. OK, so with quality hose, this is a $20 project. Don’t even dream of going ultra-ghetto and leaving those vent lines dangling. I won’t go into the inner workings of OBDII, but trust me, the system checks and IT WILL toss a code.

No, don't buy a used canister. Those are all either clogged, or half clogged. No, don't be a dick and sell your clogged canister on e-bay.

For those who need visual stimulation, here's a PDF

 

I just love reading all your responses Marcus. Always very informative regardless if i'm having an issue or not.

Cheers,

KRis

 

Absolutely brilliant! Sounds like yuov've nailed the problem.

I will check out the cost of a new filter, and if it's outrageous I will do one of the workarounds. Do you think it would be possible to just unclogg the filter? Even if I cut a hole in it, took everything out and sealed the hole back up?

Anyway,thank you VERY MUCH for your help. Made my day. Thannks

 

"would be possible to just unclogg the filter?" you would have to take the canister apart and replace the charcoal.
MarcusF a.k.a. Mr. Wizard. YOU DA MAN!

 

I'm just glad you guys recognize that I'm trying to be humorous in various parts. That and I can see the issue with not wanting to spend an hour trying to fill up.

The factory part has a current list price of $416 and GenuineMercedesParts.com has them for $333. If it cost $100, I'd consider buying one.

You might be able to hack yours in half, pour in some fresh pellets and seal it back up (it must be air tight). Alternatively, if you'd like to make something, you could use an oil catch can (not a vent) or just buy any aluminum can with a screw on top, tap some fittings, and clamp that in where the old one sits. Make sure it's sealed and you're in business.

If you go to Amazon.com and type in Vapor Canister in the search engine and you'll see several that "could" be made to work.


Personally, the $10 solution. Several clamps, some hose, and a tee. Just stop filling the car within 10 cents of when it clicks. With the $10 method it really is full with the first click.

 

As Always, you're the man Marcus.

 

Actually, I have a cheaper and easier solution (which I never would have come to without your excellent advice, THANKS AGAIN!!!!!!!!

Because it's freezing cold up here I had no desire to jack up the car and do your $10 fix. But needing gas I had to do something. So I bought 10' of the thin air tube line from a pet store (the stuff you use to connect air pumps to stones, filters, etc.) and went to a gas station. Through trial and error I found that by inserting about a foot of the line into the gas filler (where you put the nozzle), then squeezed the nozzle in. It's a tight fit but it can be done. I just rested the rest of the tubing on the filler door, but you could certainly cut it if you wish.

Now I was able to fill the tank. Yes, it took a a lot longer than normal, as I suspect the tube was squeezed and could only move so much dispaced air from the tank. but I was able to fill it up in about 10-15 minutes.

I willkeep doing it that way until the nice weather arrives Funny thing is that while the filter is still obviously clogged, it doesn't throw any error codes, malfunctions or warning lights.

Thanks again.

 

To expand on MarcusF's excellent post, attached some pictures (e.g. clearly, this ain't your Father's Oldsmobile).

 

Is the purge valve the same thing? Or seperate cannot see diagram on my small screen phone. Or do i just need to replace charcol canister?
Thanks or the help

 

Reviving this old thread because this recently happened to me. I went to the gas pump and it was instantly clicking. It was so bad fuel was not entering at all, leaking everywhere.

People in here who said the venting of the tank is done in the Canister are right. I first removed the whole assembly (Fuel canister with attached Vent Valve).

Then I blew compressed air (4kPa) in the tank hole, air was coming out of the ** To Engine** line but no air was coming out of the vent hole.

Then I blew air in the same hole (from tank) but I blocked the To Engine hole. (6kPa). Air finally came out of the To Vent Valve hole.

Because I was not able to test the solenoid for the vent valve (two pins two close to each other for crocodile type clamp), I reinstalled the canister without it. Went to the gas station and it was perfect, gas was coming in the tank like a brand new car.

I'll update my tests on the solenoid, was it the canister that was clogger, is it the solenoid or valve not opening.


Canister reinstalled W/ vent valve line.



Fuel canister diagram from WIS.

Vent valve w/ cover and filter.

Vent valve w/ solenoid

Vent valve Solenoid

Vent valve Solenoid #

Vent Valve reassembled.

 

I just wanted to update as well, had a P0450 error (pressure sensor in tank) and found this thread. I did not have a P0455 but I tried everything else so gave the $10 mod a try. On start up the check engine light went off! Worked perfectly and can now fill up the car again as normal. Symptoms were really only the code and check engine light. Fueling was not too bad and would work if the nozzle was pulled out of the hole a couple inches.

Hoping anyone with P0450 code sees this and can avoid some troubleshooting I had to do to fix.

 

Having same problem - fuel not going in. No codes. Tried the $10 mod but still no go. Pushed a solid wire down the inlet nozzle and felt a flap blocking the line about 12" down. This flap pivoted easily when gently pushed with the wire - open and close. Found I was able to manually add fuel when the flap was kept open. Any ideas about this flap?. What controls it, etc?

 

I've recently fallen victim to this same scenario when trying to refuel. I'll have to look into it. My car just turned 110K miles. CLK55.

 

I’m going to fuel up and see if bypassing the canister mitigated the problem. I just replaced the hoses and removed the canister altogether. Pic was taken before adding the last 2 3/4” clamps on the tee.

****Update, this worked for me as well. Good to go now!

 

My CLK 320 is having this same problem. Will a P0171 or P0174 code come up with this problem? I already changed the purge valve solenoid in the engine bay. Also will this fix of eliminating the vapor canister affect emissions testing? Thanks for any help anyone can provide.