Thats where your fuel lines are

 

That's kinda Obvious isn't it.
I'm just new to the diesel world, not mechanics. I'm not completely stupid.
I know where the lines are I was meaning that I couldn't tell exactly where the leak was coming from: Filler Neck Hose, Feed Line, Return Line etc.
I went out today and had another look see and the only thing I could find wrong was the little 1" by 3/8 hose they use as a cap is torn. So I'm guessin this is where it's coming from maybe? Why is it capped off?