Bent flap inside fuel filler

Question

I have a 2001 Ford F-150 pickup with a gasoline engine. There is a thin metal flap on a spring that is supposed to cover the opening in the fuel filler neck, which the fuel nozzle would normally push out of the way for fueling.

While I was ineptly trying to add fuel from a poorly designed fuel can, this flap got bent and no longer covers the opening completely.

1. What is the correct name of this flap?

2. What is its purpose?

3. Is it a problem that it is bent?

4. If it is a problem, what is involved in fixing it?

I hope I've described the part clearly. If not, I can try to add a photo.

Answer 1

The flap is called a "rollover valve". It is there to help prevent fuel from escaping in the event of a rollover. It also has the added benefit of helping to prevent fuel from being syphoned from your tank.

Unless the CEL / MIL / idiot light comes on, just leave it as it is. A number of cars do not have this flap, and work perfectly fine without it.