When my surname was Jin Liang, my father told me that I was Manchu, but what was my Manchu surname?

Shi surname is one of the common surnames in China, which originated from different historical and cultural backgrounds. According to the information you provided, I guess your Manchu surname may be "Shumulu" or "Shi".

"Shumulujia" is a transliteration of Manchu "Sumuli", which means "deer" and is the most popular name in Manchu. "Stone" is also one of Manchu surnames, which originated from "Sila" in Mongolian, meaning "red" and later evolved into "stone" in Manchu.

However, this is just a guess based on the information you provided. The specific Manchu surname needs you to know more about family history and genealogy. If you are interested in family history, you can consult your family elders or historians to learn more about your family background and the origin of Manchu surnames.