Using the new 4.1 flying template, i have created a fuel system tutorial. However you can apply this to any system you want.
This features creating a value which constantly decreases, but decreases faster while using boost. Then we create a pickup which increases the value upon overlap.
We then output the value to the HUD blueprint and then using the append nodes for strings, we create a little HUD.
Hope it helps, i would recommend checking out my draw text and hunger system tutorials before trying this.