Mercedes: Mercedes 300E 1999 - Satrting problem and Turning off while driving, shutoff valve, fuel pump

Question
1.- When i start the car and then turn it off it will not start again untill i wait at least 5 to 10 minutes before trying the switch again.

2.- It will turn off suddenly while im driving it, and i have pull over and wait 5 to 10 min untill it starts.

I was told that it could be ethier the fuel pump,fuse or relay?

I thank you in advance and would appreciate any help givien on that matter.  

Answer
Is this a 1999 E300D Turbo = E300 Diesel Turbo?
As I recall, the shutoff valve is vacuum.

When you say "not start again" do you mean it will not crank the engine, or crank but no start?

On the 1999 Mercedes, step one of any diagnosis is to scan for codes, your local dealer has the best tool for this.