This is a box that recirculates unused fuel and fumes...different style boxes were installed depending on the age and model of the car...some unspent fuel goes back to the fuel tank; one line may go through the trunk floor to vent to the outside.
The hoses can become corrupted and loosened from the tank. This can cause a fuel odor in the trunk.
Some fuel recirculating boxes are smaller than others, some earlier ones were on the passenger side and were a junction box rather than a holding tank.
Richard M, NYC
