Diesel fuel drip

Hi guys,
I have a diesel fuel drip, just under drivers side foot well, where the frame starts to curve up.. It's coming out of what appears to be a return line that runs parallel with the supply line. This line looks like there is a piece of piece of fuel line covering this "transitional" piece of plastic fuel line that connects to what appears to be a quick-connect near the bottom of the lift pump. Beyond the quick connect, by feel, it seems to have perhaps a banjo bolt holding it on the far end with an affixed "brace".
I can't tell what is causing the drip (leak)...it only happens when running. Perhaps rust/corrosion? I can't figure the hard plastic line failed?
Before I go in deep, it would be good to have some background if possible.
2003 3500 SRW 52,000 miles
TIA.
N

 

You need to go upstream to locate the origination of the leak,it will trail down with gravity.It could be as simple as a loose banjo bolt,careful font over tighten they can break

 

Thanks for the response. It looks like I was researching the wrong part/area. I think the line problem is the line that starts at the back of the head, makes it's way down along side the fuel filter and then has the quick-connect for the plastic hose-

As shown here- https://puredieselpower.com/dodge-products/5.9l-cummins-injector-fuel-return-line-3957287.html

It doesn't look like much fun undoing the Banjo-Bolt(s), especially at the back of the head.
I'll give a try on the tightening theory.
N

 

Everything was tight, looks like a line replacement. The "Banjo" bolt on the back of the head area looks like a bugger to work on. Any hints from those that have been in that area?
N

 

It’s not fun but doable,have you put a wrench on the bolt yet?It normally just takes a very slight turn if it was from there.Clean the area using brake clean and compressed air,a bright led flash light works good and sometimes an inspection mirror.Once you are all set up to inspect have someone else start it up so you can see it before everywhere is wet again.

 

The Banjo fitting near the filter was plenty tight. There is corrosion on this line and I suspect things have become a little "porous". If it's not coming out of the (steel) line itself, I suspect it's where the brace was attached to the line. Geno's has some listed but don't match what I have found so I guess it's off to Cummins tomorrow to check for accuracy and order parts.
Thanks.
N

 

My return line is leaking where it comes out of the motor. It is some sort of plastic snap ring with a ruber 0 ring inside of it. I'm having a hell of a time fixing it.Has been close to a month can't get the problem solved!!