Abstract: A diagnostic fuel storage system is provided and includes a pressure sensor configured to monitor pressure at one or more diagnostic points within the system. In accordance with one embodiment of the present invention, a diagnostic fuel storage system is provided comprising at least one storage tank, a filter system, at least one pump, and at least one pressure sensor. The storage tank includes a fuel vapor vent port. The filter system comprises a filter input port coupled to the fuel vapor vent port. The pump is positioned to cause fuel vapor to pass through the filter input port. The storage tank, the filter system, and the pump are arranged such that the storage tank and selected fuel vapor ducts in communication with the storage tank operate below atmospheric pressure. The pressure sensor is configured to monitor pressure at one or more diagnostic points within the storage tank, the selected fuel vapor ducts, and combinations thereof.

Abstract: A fuel storage system is provided including a storage tank, an exhaust port, a filter system, a primary pump, and at least one secondary pump. The storage tank includes a fuel delivery port, a fluid vent port, and a pollutant return port. The filter system comprises a filter input port coupled to the fluid vent port, a fuel vapor duct, and primary and secondary filter output ports. The fuel vapor duct defines a flow path extending from the filter input port to the primary filter output port. The primary filter output port is coupled to the pollutant return port. At least a portion of the fuel vapor duct forms a permeable partition designed to pass a non-pollutant component of fluid within the fuel vapor duct through the permeable partition and designed to inhibit passage of a pollutant component of fluid within the fuel vapor duct through the partition. The secondary filter output port is partitioned from the fuel vapor duct by the air-permeable partition and is coupled to the exhaust port.