fuel problem cant doesnt start in mornings

[noo noo]

can somebody please assist as every morning the fuel has drained back in to the tank when i am trying to start the car. the car is a Mercedes e320 diesel w210 2001 estate. my mechanic has checked a few items like air leaks around the engine but he is lost as to what the problem is. can anybody throw any light on it and help please

 

[renault12ts]

Replace the plastic fuel pipes and o rings.

 

[Terry_]

Replace the plastic fuel pipes and o rings.

+1
You'll not see a leak as such, but the 613 engine uses vacuum to suck fuel on the low pressure side of the system, so any seal that isn't air tight will cause hard starting.
An injector with excessive leak off will have the same effect, although this tends to happen more on hot / warm starting

 

[Herishi]

I get this in my s211 v6 I have to turn the key to pos2 and wait 10 seconds before starting the engine