Re: First post - recently joined - GFCI without a ground wire
Is this a 60's house? Next time you are over take a look at the box the outlet fits into (shutting off the power first of course). Its possible that the box was grounded but that no ground wire was extended out to the actual device. With the outlet out of the way you should be able to see the wire as it feeds in and is clamped, and the coloured line and neutral wires, if you are lucky a bare copper wire will also emerge and run to a large screw at the back of the box.
If this is your situation a bare section of copper wire (of the appropriate gauge) can be added to connect between the outlet ground and the box ground.