A fuel storage system has a tank access chamber with improved monitoring, servicing and maintenance capabilities. In particular, the chamber includes a sump monitored by a liquid sensor whose proper function can be automatically checked remotely, e.g., via an electronic controller or remote manual operation. In cases where such a check indicates a need for physical inspection of the sump sensor, the present system provides for sensor removal and installation by service personnel from a location outside the tank access chamber. Thus, the present system facilitates regular inspection and routine or unplanned maintenance without the need for a person to physically enter the tank access chamber.