Hi again.  My new 2004 Vibe's fuel tank wasn't filling up.  The pump would fill for a short time and then keep popping out even though the tank wasn't full.  Took it in and mechanic cleaned out a vent line and found a hardened powdery white substance that he unclogged.  He said to try filling up the tank before he replaces the evap charcoal canister.  Great news is I filled it up all the way to the top.  No problem with the pump popping out. 

He showed me inside the gas filler that there was a similar white residue on the sides of the tank wall.  Photo to link above.  Does anyone know what this might be and if it's something to be concerned about.  The 2004 vibe has 43K miles and no check engine lights and drives well so far.  It's a manual.

Thanks for the help!

https://photos.app.goo.gl/efj7CtoAZkF1owtXA