Blowing over the top of a Coke bottle sound

[KRAM36]

Man you guys must have some quite cars to be able to hear this sound coming from the fuel filler door area.

[Fuzzuki]

I placed a rag around the filler nozzle to see if it blocked this damn noise.

It worked.

Now at least I know where the noise is coming from

[Fuzzuki]

what is actually making this silly noise?

[Jager]

Use duct tape to cover the vent hole to verify.