My garage floor was painted when I moved in and the house was new. I'm selling the home now so I am filling the cracks on the garage floor and after it's patched I will repaint it. I am using a scraping tool and removing the paint from each side of the crack before I repair it as I think that's the right thing to do. I think I will have to acid etch the floor before repainting it. Will the acid etch process remove the rest of the old paint or will I actually need to make the concrete paint free before applying the muratic acid? (not sure about the spelling).

Parts of my garage floor get piles of the white powdery stuff accumulating on it. I think this is lime leeching out of the concrete when it's very wet outside. Some of the cracks I'm patching also have the white powder about 5 inches on either side of the crack. On these cracks I'm using the same simple pre-mixed concrete crack filler that comes in a big squeeze bottle. Do I need to fix these cracks with the real injection water resistant expensive stuff to fix concrete cracks?

Any advice would be appreciated.

I would simply fix the cracks like you have been. If you are selling the house I wouldn't worry about a 20 year fix. I would let all the patches dry and cure, then hose down the floor, use a ruff bristle push broom with some warm soapy water and scrub the floor. Wash it out again with a hose and squeg. Let it dry and then paint. I wouldn't go overboard with the check book seens how it isn't necessary.
Mike

Well once again I couldn't add to your reputation but thanks for the solutions. That is exactly my position. Looking to sell a house in great shape with everything together but not looking to spend my $ to insure they have no repairs for 20 years. Thank you and I'm relieved that I don't have to mess with acid. I'll let you know how it went in a couple of weeks.

I don't think you mentioned what you are using to patch the cracked concrete but I would suggest a paintable caulk rather than cement patch. That crack means there is slight movement and shrinkage in the original pour and no patch will stop the movement, it will crack again.