Doesnt your car have the priming pump? My 84 300SD has one, if you run out of fuel all you have toi do is unscrew the pump knob and pump away until the line is primed. I dont know what Mercedes you have, but I know the 3.0 Turbodeisels had them. Not sure about the 240 though or the normally aspirated 300. Does the veggie system bypass that priming pump?