W212 Absorber Valve Problem

[bergut]

A 2010 W212 was delivered, smelling of gasoline. Diagnostics revealed no issues with the front and rear EVAP valves.
When activated, everything works, but when the car is started, the front valve does not work. I manually closed the rear tank valve and disconnected the connector. The problem is solved, but I need to troubleshoot because the fuel tank is bloating.
What could be the problem? Should I look in the coding or in the engine control unit?

 

[tsulovari]

What engine do you have? The front purge valve is normally closed and the rear exhaust valve is normally open. The best tool for checking for EVAP leaks is a smoke machine. You close the tank valve and check for leaks. Your EVAP canister may be faulty, which is why your car smells like gasoline. If the fuel tank is constantly overfilled, gasoline gets into the charcoal canister and damages it.