I had a fuel gun held at the AA check-in counter when I went down to Puerto Rico for their Latin Cup. They smelt some fuel residue and was not comfortable with that. Not even to place in my checked luggage.
Fortunately for me, the country manager for AA was my next door neighbor and I simply told the check-in girl to give it to him. I got it back when I returned.
So, make you wash it out with detergent.