It will release when opening the 17mm bolt, always works for me (I just open it slowly, should have added that). It will be easier to remove it from the rail seeing as though he is fitting a new rail. It's easier to open that 17mm banjo bolt when fitted to the engine, instead of sticking the fuel rail in to a vice or something after as that bolt is usually fairly tight. I'm really not sure tbh mate, sorry dude. I'm sure someone else will confirm though.