erikderby

Hi, I hope someone can help me with any experience they might have. I have a 98 slk230 that is reading a P0440 code / evap malfunction. It only happens when the fuel level gets down to about 1/4 tank. After this happens, it starts to cause random misfire codes and the engine runs rough. If I turn the car off, fill it up with gas, restart it, the problem does not come back.

If I never let the fuel go below 1/2 tank I would never know there was a problem with it. Any ideas on where to start checking? I've already got a new gas cap on there.

ohlord

1`the tank is getting filled with fumes that should be evacuated from the tank by the emissions system.
Start by checking your purge valve.The lines to it and clean it.
Diy write up in the diy section on w210 forum www.benzworld.org
If that purge valve is clean and ticking away like it should and the cel does not clear then you need to inspect failed or leaking tubes to your charcoal canister.
Start with the purge valve

Also don't top off your tank when filling up
just shut off at the first click of the gas pump