I think Donbrew is correct on every count, and I’ve often wondered why more motors don’t have electric oil pumps. I did use “flood mode” to start when I was dealing with a P0172 and it was so rich when cold that it really WAS flooded.

I’m a bit skeptical about how much harm a couple second of low oil pressure at no load could do, but the potential benefit of “priming” the system is obvious, and I don’t see any harm except maybe working the battery a little harder. If GM thought there was any benefit, it could easily be programmed into the ECM, and even consider how long it’s been since a start or whether the oil life meter has been reset, so that the driver could simply start like the manual says, without touching the gas pedal.

Now I wonder how turning the key and letting the fuel pump run for a couple seconds could give smoother starts. It seems ensuring no lean condition for the first few seconds due to low fuel pressure is a plausible explanation.

 

As I said in post #2 priming the fuel pump does give a quieter start.

 

Thanks for clarifying, I think this procedure would be ok for first start after a timing chain change or oil and filter change, but not necessary for every day driving, but maybe after it sits for a few days.