Please describe your situation a bit more in detail.
How is the gps connected, what kind of storage device is it etc. Not least - the file system
And your fstab file
What you could try is to add "user" (no quotes) to the fourth field of its entry in fstab. Fields are separated by space, separation by comma (,) is done in the fourth field as there can be several options
Be careful, an error and you might not be able to boot properly. You will however end up in a TTY and be able to edit fstab.
Don't fix it if it ain't broken, don't break it if you can't fix it