Maybe. I pulled the tank venting, the EVAP tubing and fill tube and blew air through them. Blocked everything and gently pressurized the tank with a rafting pump. I don't know, it actuated some valve somewhere. I put it all back together and went to the last place that was ************ to fill and it filled fine. We'll see, haven't filled it since. Will try again in the next day or two. Sorry we're highjacking though so ping me or start another thread about it, it seems to be a GM thing and might be a good resource.
-G