Autozone or Oreillys just may have a fix for that fuel line. willwren is right about it being special, but a company called Dorman makes replacement ends and fittings as well as lengths of line for the hard plastic high pressure fuel lines, including splice kits. I know oreillys carried them when I worked there, and I know autozone does too. You may have trouble finding someone who has enough experience to actually know what they are since they're not a common thing the average 17year old at the counter knows anything about. You may be better off searching their very slow website for what you need, and showing them that.
The dorman part number for a "5/16 nylon to nylon compression union" is an 800-145 for a 1 pack, or a 800-147.5 for a 5 pack. Those are coming out of my master kit here at work.
I believe their website is http://www.dormanproducts.com/
This is all assuming that you guys are talking about the same high-pressure hard plastic/nylon lines that I am. If not, ignore me.
Hope this helps.