Back in the day when aGM fuel pressure regulator had an diaphram leak it would flood the engine as it leaked down after shutdown . If the car sat for an hour or so it would have extended crank times on the first startup and be fine after that if you started it right away or left to sit for several hours where the fuel would evaporate. Fuel would leak through the vacuum hose into the intake manifold. If your fuel pump was bad it would just never start. Throw a fuel pressure gauge n it and watch the pressure at startup and see if it drops slowly after shutdown.