Having used Maemo Mapper through a number of releases, now 2.6.2, I've never made a deliberate effort to use sqlite which wasn't used when I started. My map data bases are all .db. The name and location of the db file for each map source can be found in Maps-> Manage Repositories. I moved my maps to the internal card /media/mmc2/OpenStreet.db. For my local area they are about 4MB in size. I suggest you move you maps to the internal card which has more storage space. Your problem may be that the main storage doesn't have enough free space for your maps which all depending could be considerably larger than my 4MB. I looked in the configuration files and couldn't find a parameter for whether to use sqlite or the old format.