Most often that is caused by overfilling, pumping gas after the handle clicks off.

 

Yes In fact I did. The first time it happened I concluded it was the purge solenoid valve malfunction under the bonnet/hood. After replacing the solenoid and the charcoal canaster a few days later it happened again. Soooooo. after weeks of bashing my head against the wall ...........
1- No, Filling and topping off the tank has nothing to do with this issue.
2- I removed the canister and set it up away from the house and connected my shop vac exhaust to it in order to dry out the canister.
In addition I disassembled the old canister for inspection. no issues found. The check valve worked perfectly.
3- I removed and cut open the fuel filter for inspection no issued found.
4- I tested the pressure sensor in the tank. No issues Also there is no way you can over fill the tank and cause this issue. It fills and the pump stops
5- I tested the purge solenoid and checked for the proper signal from the ECU. I had signal but the "New" purge solenoid valve was stuck open with a very powerful suction at the canister.
6- I replaced the purge solenoid valve, new from MB. Installed the dried out canister Replaced the fuel filter Again.
The car has performed very well since.
So I replaced the purge solenoid valve with a new defective one and the problem repeated itself.
The purge solenoid valve was the issue all along.

 

Thank you for the update!
By the way, do you have the MB part number for the purge solenoid valve? Thanks

 

A 000 470 37 93 PURGE VALVE / 2003 Mercedes SLK 230 Kompressor

 

I found the part on amazon.

Anthony, Thank you very much! So if the purge valve is stuck open ( vent to the outside world ). The fuel tank will not build up pressure and allow over flow into the charcoal canister. Is that a correct summary of the behavior?

I am going to tackle this repair at the end of august. Right now my car is driving well. I had already bought a new fuel pump and new fuel filter. Any advice on doing this repair to minimize gas spillage?

 

I think this is incorrect valve. The Crossfire has the plug coming out sideways.

mercedes benz purge valve 00047071


I think this is the right valve. https://www.apbparts.com/store/p6250...html?locale=en

MERCEDES C320 CL550 2001-2012 FUEL PURGE VALVE 0004704993

 

That is the check valve. Its open or closed.
You need the purge valve under the hood.
The purge valve only scavenges off the vapors. Its computer controlled. it just "sniffs" the vapors and allows them to burn off.
If it sticks open it will draw fuel into the canaster and eventually up to the engine. The engine will run erratic and stall. Not idle. It will be running rich.
Make sure its a Mercedes part!

 

OK now this is starting to make more sense. So the purge valve is under the hood, the check valve is part of the canister. I had replaced my purge valve and that's when my troubles began as I had acceleration and hesitation issues.
See my very long thread: https://www.crossfireforum.org/forum...eleration.html

I had replaced that valve as I had an engine light and high pressure on the tank. So my new part is very possibly bad. Here is my current status of the purge valve.

Blocked off

Again thanks for your help on this. It's a very complicated system and even reading the service manual, all the nuance slips by.

 

Thank you for the part number, and thanks for sharing the solution. Mine is working currently, but I think I'm going to pick this part up to have on hand.
BTW, I'm on SLK World as well. I wonder if this one will work? mercedes-vapor-canister-purge-solenoid-0004703593 It's for a n/a engine, 2003 SLK 320.