wont stay running
 

I have a 2003 Nissan UD 4 cylinder diesel box truck.I had a fuel line leak and I cut out bad section and replaced it with approximately 2 feet of rubber fuel line grade hose.after I completed this task the truck ran for 20 minutes and drove around the block and died when I got back.the line that I replaced is the 1 that goes to the top of fuel filter. I can get it running by filling the fuel filter .it will run for about 20 minutes until fuel is gone from fuel filter.is the line that I cut a return or supply line from the tank? it ran just fine before I did this.I was just leaking all over the place and making a mess of driveway