My car is a 1991 Mercedes Sel 420. I get up in the morning and I start my car no problems at all, I can drive for hours and have no problems but as soon as I turn it off and go in a store and come back the car hesitates to start. I crank it on it starts for 5 seconds then it shuts down, after about the third or fourth try the car stays on. Sometimes I get it started and take off 10 seconds later my car shuts down with lights all on the instrument panel. My car never idles different through out the day. Its so weired!?!. I was thinking that it may be a fuel check valve and fuel accumalator but replaced both check valves and the accumalator and nothing different. I also here that it may be the CRANK SHAFT POSITION SENSOR. would a crank shaft position sensor allow a sel 420 to start at all? My car after cranking for a little while will start for 5-10 seconds before it stalls out. once it cools a little bit it will start with no problem. Thanks for reading!!!