CDN BJ70 fuel tank vent hose

[Capitalguy]

I have a quiestion maybe someone can ansewer, when I fuel my truck and take the cap off I get a vacum release, thinking this was normal I never paid any attention to it until I read here on mud that the tank should be vented. (The truck has always ran great) The enclosed diagram dosen't really show a vent, they have something called a Check Valve, is this a vent of some sort that can be taken apart and cleaned?

Thanks

 

[audaciousduo]

Just pulled a tank hope this helps.

 

[Capitalguy]

Thanks for the pictures, I'll remove my access panel in the wheel well and take a closer look at what they are calling a Check Valve in the manual, In one of the posts I searched on mud, says that there always seems to be some pressure in the tank. Maybe I'm trying to fix something thats not broke.