I have a grapefruit tree in my backyard in Los Angeles that I planted about 12 years ago. It started giving fruits a couple of years ago, but the fruit is smaller than a small orange, very bitter and the skin turns yellow in August. Is there a chance for this tree to produce normal grapefruits or I should cut it?
I wouldn't throw in the towel yet.
I would first recommend a soil test. This can really help determine what may be missing in the nutrients or what corrections can be made in amending the soil. Since you said you have had poor fruit since planting this could very well be the issue.
Water and proper amounts on Nitrogen and Phosphorous are very important.
Environmental issues can be responsible for many citrus fruit issues.
I have listed a few links for you to refresh you on the care requirements.