fuel pressure

[sea-doo daddy]

Does anyone know if there is supposed to be pressure in the fuel tank? Because when I take filler cap off of tank to fill w/fuel it releases preasure to the atmosphere.

 

[Meme N Pop]

I'm sure pressure builds up. That's why it has check valves to be able to release it.
I don't know how much pressure has to build up before this happens though.
Maybe someone else will answer