any idears why vauxhall vivaro 2015?

You have lost something: The ability go have a look and work it out.

Th epipe soulds like a fuel pipe. It has either broken or come off from its coupling. There won't be much to choose from if you have a look at where th epipe is hanging, where it probably went and you may even see from whence itcaame.

If the van is a 2015 model, it may even be in warranty. Ring the garage and check before you start fiddling.

If you play your cards right you may even get the fuel replaced for free.

And don't smoke whilst you are anywhere near it.
February 2016