1989 Mazda 323 engine gets flooded. What causes this? All cylinders get flooded, as if the injectors are over activated.

 

Holding your foot on the gas pedal while starting will do it to start. It can also be caused by a faulty injector if one cylinder is getting flooded. It can be anything from a bad PCM, to wiring harness problem, or even a pressure regulator diaphragm ruptured, or too high fuel pressure.