what year did gm change to fuel injection
Chevrolet introduced a mechanical fuel injection option, made by General Motors' Rochester Products division, for its 283 V8 engine in 1956. It has become the primary fuel delivery system used in automotive engines, having replaced carburetors during the 1980s and 1990s.
I was going to say it depends on the model, the engine option, and which side of the border you are on! There were also the few years when it was a hybrid carburetor, with computer control of a semi-normal unit. I'm afraid there is simply no one correct answer to this question.