Been about 2 years since I last posted, anyways I completed my mini me swap (D16z6/D15b7) and decided to replace the fuel filter, because why not. I currently have a fuel leak coming from the feed line into the filter (I think I cross threaded it woops). I did some research just incase there was a gasket that I was missing and realized I have this fitting on the line that only seems to be on my car? Thought I post here in case there is something I'm missing for sealing the fuel line, but all diagrams and pictures I have seen don't have this fitting. I'll post pictures below but, could anyone tell me if someone before me did this or if this is original.

Also I don't know how to resize photos on here sorry they are so large,
This is for my 1993 Del Sol, thanks.

 

Someone did a dumb and cut that fuel line and used your mystery fitting to fix it.

It's appears to be a 1/4" compression fitting from the plumbing isle of your local hardware store. Those compression fittings are mostly one time use and not for vehicle fuel lines. They are also not the correct size for the metric fuel lines on a Honda.

 

You probably ruined the new fuel filter trying to thread that fitting.