Combined open vent and emergency relief vent

A fuel tank, comprising:

• a tank, comprising:
• a tank housing defining a tank cavity configured to store a fuel therein;
• and
• a port defined in the tank housing in communication with the tank cavity;
• and
• a venting system, comprising:
• a base attached to the tank housing, wherein the base defines a base cavity in fluid communication with the tank cavity through the port;
• and
• a relief housing movably connected to the base, wherein the relief housing is movable between a first position and a second position, wherein a sealed interface is defined between the base and the relief housing when the relief housing is in its first position, wherein the relief housing comprises an open vent aperture in fluid communication with the base cavity, wherein gas may vent from the tank through the open vent aperture when the relief housing is in its first position, and wherein the sealed interface is unsealed when the relief housing is in its second position to expose a relief vent aperture in the base.