Hi guys,

I have a fuel tank which has a vented cap as well as a breather pipe for air to be drawn in for contraction and offset the vacuum during fuel flow but not sure whether I should have a one way valve in the hose so it can draw air in but not let fuel out (the hose end is higher than the fuel tank)? Obviously air will still be able to escape via the vented fuel cap during expansion.

Does anyone know if there is a one way valve in the factory tank?