202 Elantra Fuel Leak

I cam out of my house this morning and noticed a large wet spot under
the back of my car. Upon investigation it appears to be a fuel leak
from a black vented box that is immediately behind the driver side
rear tire and connected directly beside the gas tank. there are 2
hoses that appear to be fuel hoses going into the forward end of this
box. I disconnected two mounting nuts and looked inside but it is an
enclosed box mounted inside the casing. I can't find any info on the
net or any illustrated parts lists. Can anyone give me an idea what
this box is and why it might be leaking fuel?

I did fill up my tank last night and I "topped" it off to round the
price. My car also parks on a fairly decent slope in my drive way
rear end first.

Thanks for any advice!

 

The box to which you refer is the charcoal canister. It should never have
liquid fuel in it, only vapors. It's likely that the fuel is there
because you continued adding fuel after the automatic pump shutoff,
overfilling the fuel tank.

Remove the larger hoses from the canister and drain it. Then reconnect.
If the check engine lamp comes on in the near future, it's likely you've
damaged your charcoal canister and will need to replace it.