Fuel Tank for Injection Engines

[alga]

I'm pretty sure it must be a two-way affair. It must allow air in when the petrol is being used, and it must allow air out for thermal expansion. I just used a 1 m length of fuel hose, from the right rear corner, where the breather port is in the tank, it runs up to the chassis, then left towards the opposite corner and down. Previously it used to be just up and down, but that used to spill fuel on heavy cornering.