[Keith-i]

Looks like the fuel delivery pipe from the HPFP (high pressure fuel pump) to the fuel rail. Also looks like someone has tried some ptfe tape to seal it. I bet the connections is damaged where the pipe seals on. Possibly 059130309AH

 

[Keith-i]

If it's the pipe I think it is, it's under serious pressure so no amount of plumber's tape will hold that one tight.