I Did something stupid and now I have a piece of plastic in my gas tank.

What is your question?

I was trying to prop open the little silver thing so that I could get a gas can nozzle into my gas tank. I thought I could prop it open with the plastic knife and after I got the gas into it, the knife broke off And went into the tank!Thank you so much. The knife will float when I put it into a glass of water if that helps. Do I have to pay to have this piece of plastic remove or will it simply float or is it still in the funnel.