I have a Chevrolet 3500 with 6.5 liter diesel engine.
This morning didn't want to start. Battery is good.
I crawled under it and I found out a fuel leakage.
Any idea what part is that? Leakage shown with the red arrow.

 

Fuel line connector, there's an o ring in there

---AutoMerged DoublePost---

That cannister is a fuel filter looks like it wouldn't hurt to change it.

 

Thank you!
Is there any special tool to tighten that o ring?

 

Push in the 2 little tabs on the connector and pull the line off , put a new o ring on and push connector back on till it clicks on. There's no tightening on an o ring