Fuel line retainer clip

[alpinegreenneon]

When you say “black piece”, do you mean this part? View attachment 576755

I thought it was part of the male connector, so I didn’t even try taking it off. But it now makes a lot of sense if it does come off, because otherwise I can’t get the green piece off…

Yes. The black piece and the white piece hold the o-rings in their grooves. The fuel line in the pic I posted is from my '98 Neon. On a Neon the metal male tube looks like the plastic male nipple on the fuel rail. When the metal tube gets rusty on a Neon, things come apart like yours and I have to reassemble everything into the female connector.