sfag

My 98 230 chuggs when I try to put the boot down especially after deaccelaration. It will continue chugging with loss of power until I stop and release the petrol cap. Any ideas. Is it something to do with filling the petrol tank up to the very top ?. The problems happens even when the tank is half empty.

thanks in advance

Brian_R170

Sounds like a problem with the fuel vapor recovery system. Yes, filling up the fuel tank to the very top can cause problems with the fuel vapor recovery system. However, the first thing I'd try is a new fuel cap.

sfag

will try a new cap. The car is in garage today. They gave it the usual 'computer diagnostic's' test which did not show any problems. I'm not sure if they know what the fuel vapor recovery system is??. Is it located inside the tank. Is it a simple device.

thanks again.

Brian_R170

The fuel vapor recovery system is designed to trap fuel vapors when the car is parked and then burn them in the engine again when the car is started. I don't know the specifics of the SLK, but generally, the system consists of a cannister of charcoal that is connected by hoses to the fuel tank and the intake manifold. There are also some valves to keep everything flowing in the right direction. The fuel cap is also part of the system because it is required to keep the fuel vapors from escaping when the car is parked and to maintain a certain negative pressure inside the fuel tank when the engine is running.

Sounds to me like you have too much negative pressure in the fuel tank, but if this is only a recent problem, you may have just overfilled the tank and got liquid fuel into the vapor recovery system, in which case it just needs to be purged of liquid fuel.

sfag

Thanks again for the infor. Very informative. Alas came back from the merceedes garage unfixed. Their “computer said everything was AOK” so no solution from them. Will furnish your info to the garage the next time I take it in.

sfag

Got my problem fixed. It was an air mask. The symptoms had changed by the time of my next visit and by then a simple switching off and on of the ignition resolved the problem. I guess the vapor recovery filter cleaned drained itself when I stopped filling the tank to the top. A new air mask cost £300 fitted.
Thanks again