Mercedes Benz repair: hard start, vapor lock, fuel distributor

Question
have 1975 450 sl.  becoming hard to start when
warm/hot.  replaced fuel filter/plugs. cap/rotor. 'trigger points'.  what's up ?
this is maddening ?  i'm not a tech/mech.


Answer
What happens when the car gets warm is something like vapor lock. The fuel distributor is allowing the fuel to drain back away from the distributor and there is a air lock that prevents the fuel from getting back to the injectors. There is a one way valve that should hold the fuel in the lines and it is not working.