Leaking Fuel?
 

Today while I was under my truck i noticed that my fuel tank had fuel running down the sides from the top. It was not leaking it was more like a seep. It didn't cause any puddles on the driveway but you could tell it was slowly seeping from the top and running down the sides. Also my fuel level is under half a tank. Is this something to be worried about? Could it cause a lose of fuel pressure?
Thanks for any advice guys it is much appreciated

Do you know if you have the in-tank pump or block mounted?

If it's block mounted, it would be more likely to have the return fuel fitting causing the leak. If you have the in tank pump, it could be the return or outlet from the fuel basket. If it is only a seep, there wouldn't be a noticeable pressure loss if it is an in tank pump.

The beds on these truck are pretty easy to remove if you want to have a good look at the top of the fuel basket. You can get a bore scope or mirror up there without pulling the bed as well.

I honestly have no idea. I am new to the diesel world. The truck has a fass fuel system if that matters. Also my fuel pressure gauge read 16psi.