Is220D - Takes A While To Start If Parked On Slope

[Captain Fizz]

Hello folks,

For the last 3 days, if I park my car on a *slight* incline (front wheels up, no more than 3°) the engine turns over for say 5~6 seconds until it starts.

On flat or front wheels down = Starts fine.

Parked in same place for nearly 2 weeks now, only started a few days ago.

So I'm thinking there's a pipe a little loose / connector leaking slowly between the tank and the engine...

Will hopefully have time to pop head underneath on Sunday afternoon - Will do some hunting on where the fuel gets to the engine / location of stuff, but has anyone had this before?

Know where to look?

Thanks :)