BenzWorld Junior Member
Date registered: Jun 2009
Vehicle: 1999 SL600
Location: Boston, MA
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The carbon canister is in the trunk compartment near the antenna (driver side of car). You have to remove the carpet/lining of the entire trunk to get at it. The carbon canister has three hoses coming out of the top: one goes to the fuel injector, one connects to the fuel tank and overflow/pressure relief valve and the third goes to another pressure relief valve.
Also, if you go back there you will see the fuel tank pressure vent valve. I would make sure all the connections are tight as any leak here would be confused by the car with a loose fuel cap and give you the flashing fuel gauge light.
The purge valve is in the engine compartment. I have an SL600 which has two, I believe an SL500 will only have one purge valve. The purge valve is black and has the letters "MOT" printed on the top. You can locate the purge valve by following the vacuum line that goes from the fuel injector to the carbon canister. Check all the line connections to make sure there are no leaks. My leak was at a rubber elbow in the line. The part of the elbow that attached to the purge valve was worn, I reversed the elbow connections and it cured my problem because the worn end formed a good seal with the vacumm line (i.e. I was able to jam the vacuum line deeper into the elbow).
Someone who has a V12 S600 posted some pictures on how to find the purge valve and check for EVAP leaks in his car. Different car but same principal. You could check for that thread it will help.
Also, you can clean the purge valve with MAF cleaner. There is a thread in one of the stickies on how to do this.
Hope that helps.