Question about the Quest line in Faultline
Its been quite a while since I did that quest line, and memory is fuzzy, but I believe what you are seeing is a 3-D puzzle of sorts. There are tunnels under several of the spots in Faultline, and your marker may only be showing the 2D location of the entrance. You may need to nose around for a way down.
I used to have such problem as a newbie years ago with Skyway. I sent a request for help in-game and a GM came to assist me.
Alright forget I asked... *blushes
Just noticed that there is a bridge that I can fly under and sure enough, bellow the bridge is my entry point
Edit:
Thanks for your quick reply Rodoan found it out now as you can see
I'm doing the Jim Temblor quest line in the Faultline (the one with Fusionette). I have reached the part where I am to stop Nocturne's Escape. But when I follow the Quest arrow too my entry point there is nothing there just a park and no entry points.

The quest says that; Nocturne is planning to take the route through the sewers to her pick up point near the water line. So I flew to the water line even though it is on the other side of the map from the quest arrow. But there is no entry point either. I have tried logging out to see if that helped but still the arrow points to the same spot.
I've been flying around fro some time now looking for an entry point with no luck so now I hope that some one here can help me
Thanks for your time