I have a 04 G35 and the fuel line is making a vibrating noise under the passanger floorboard. I have followed the fuel line where it goes to the engine and noticed it is making the same vibration. Any idea on what it could be? the car runs fine its just an anoying noise and it usually only does it when the car is warm.

 

Its your fuel feed hose damper. Here is the pn: 22675-AM60A. Its an easy fix. I just replaced mine and it was no problem at all. I was worried though because it calls for a special tool to disconnect the lower fuel line but then I realized I could just break the old connector since I had the new hose and it slid right off. Look on Infinitihelp.com and search for ITB06-012, that should give you an idea of what your working with.