Vented or non vented gas cap

[Dmulder]

How would I know if I need a vented or non vented gas cap?  I finally got the keys to my mini replaced but not the locking fuel cap key. So I need a new fuel cap. Thanks for the help.

[joakwin]

carb should be vented, fuel injection is non vented

[John Gervais]

If your fuel tank has a small ventilation hose connected at the top of the tank adjacent to the rear seat back and exiting the boot floor, then you actually can use either a vented or non-vented cap.  The vented cap can be a bit messy on your paintwork, as fuel tends to splash out. 

They used to sell stylish 'bibs' for the fuel tank filler neck which detracted from the stain left under the filler neck.