Have you called American Honda to tell them about the problem? If not, then Please take a moment to call them at (800) 999-1009. Press option 7 to speak to a rep. They will ask for your VIN number, will collect your contact information, and you can tell them about the problem you are having.
I also own a 2004 Pilot and am having the EXACT same issue. My dealer replaced the Vent Shut Valve, which did not fix the issue, and now Honda is recommending that my dealer replace the entire tank.
I called American Honda today to try and seek assistance from them to no avail. Honda has not issued any service bulletin or recall about this issue yet, and they will not do so unless we all take the time to inform Honda of the problem so that they know there is a larger community of drivers facing this same issue.
Thanks and good luck!
Monday, December 20th, 2010 AT 6:05 PM