In-vehicle fuel tank device and utility vehicle

An in-vehicle fuel tank device, comprising:

• a main tank comprising a top portion, a side portion, a bottom portion, a main tank section, and a sub tank in a form of an upwardly open depression;
• a first opening and a second opening each disposed in the top portion and serving as a breather;
• a first pipe connected to the first opening;
• a second pipe connected to the second opening;
• a merge section at which the first pipe and the second pipe merge with each other;
• a merge pipe connected to the merge section;
• and
• a common cutoff valve on the merge pipe,
• wherein the main tank section is defined by the top portion, at least a portion of the side portion, and at least a portion of the bottom portion,
• wherein the sub tank is defined by the bottom portion, and
• wherein a boundary area between the main tank section and the sub tank defines a curved barrier configured to inhibit fuel from flowing along the bottom portion from the sub tank into the main tank section,
• wherein the boundary area further defines at least one flat portion disposed along the curved barrier, and
• wherein the at least one flat portion connects the at least a portion of the bottom portion that defines the main tank section and the bottom portion that defines the sub tank section to facilitate fuel flow from the main tank section to the sub tank.