Auto Parts: MB ml320, car wont start, new spark

Question
Every time i go to start the MB i have to turn the key once car wont start i have to pump on gas pedal a few times and try again it usually starts the second time if not the third. when i purchased the vehicle i was told this might be a fuel problem but which part might be the cause of this problem?

Answer
    Well, first of all, on a fuel-injected vehicle pumping the pedal does nothing.  On a carburetor equipped car it pumps some extra fuel into the manifold.   That enriches the mixture and makes it easier to start.  I don't know how many miles your car has or what year it is.  I would recommend a tune-up first.  New spark plugs and wires at least, a cap and rotor if it has one.  Then check the fuel pressure.  Check it with the car cold after sitting overnight, and then check it after the car has been started.  If it is low or non-existent at the cold check then the fuel system is allowing the pressure to leak down.  You can either live with this or try to isolate the problem.  It could be in the pump, the pressure regulator, or one of the injectors.  Just one injector leaking would be enough to relieve the whole system of pressure.  But do the tune-up first, it's cheap and it probably needs one anyway.