[collin]

The full cap  is difficult to open as shown on the link below:

Fuel cap - i30 - YouTube

Is it possible to "adjust" the valve and if so how?

[sundiz]

Cleaning and lubricating the mechanism has worked well multiple times.

[collin]

Thank you,

But could you tell me were and how

[Shambles]

Well, the release mechanism is obviously working as you can easily pry the flap open.

So clean & lubricate the hinge to start off with, then clean any gunk from around the release tab and try relocating the nylon cap tether.

[Dazzler]

Hi Collin,

It always helps to have more info in your vehicle decription in this case it may have helped to know if yours was a series 1 FD model as the plastic cap teather sometimes gets into a position in that model that can stop the cover from opening easily.