sidekick
Guest
If gas cap will go on and tighten up like before, it should not matter if little flap is closed. I think it is more of a anti siphoning device than anything.(keep thiefs out)It is too far removed from gas tank to stop splash out and cap is not vented anyway.Broken off piece is too large to cause problem with fuel pump pickup so I can't see down side to it making it in to tank.Consult dealer for his opinion when you get time but I don't think it's urgent.Filler neck is usually connected to plumbing which connects to tank via rubber hose and is removable.I'm sure it could be removed from car and broken piece extracted.I tend to agree with the guys at the store.I am not a "real" mechanic.I just played one on my own stuff for 30 yrs.Good luck.