Why not set throttles higher than 1/2" during pre-start? PA-

[Gomer Pound]

I had an interesting thing happen last week. I cleaned and rotated the spark plugs on my right engine (my very first time) . I was pretty sure I did a good job. It was late, so I didn't have time to runup. The next am, I preflighted, then started the left engine. I then tried to start the right engine. It turned over, but not a hint of wanting to start. Oh, Oh, did I somehow break an insulator or reverse the wires to a plug? Iremoved the cowling and felt everything should be OK.
One of the things I have noticed lately is when I set the right throttle to 1/2 to 1" before using the fuel pump, I get NO indication of fuel flow when the pump is turned on and the mixture is moved from idle cutoff to rich. I just run it about 6 seconds, then start. So, I again started the left engine as normal. This time with the the right engine I moved the throttle ahead about 2 inches instead of 1/2" , turned on the fuel pump, ran the mixture from idle cutoff to rich, and I began to see fuel flow. I moved the mixture back to idle cutoff, turned the fuel pump off, moved the throttle back to 1/2", and the engine easily started. It even idled better than before with the cleaned plugs!
The 1/2 " setting seems to be the proper one for idling on both engines once they are started.
My question is, could I even run the throttle wide open while having the pump on and running the mixture from idle cutoff, to rich until fuel flow noted, then back to idle cutoff, then turning off the fuel pump and moving the throttle back to 1/2" ? What exactly is the relationship between the throttle position and the fuel flow meter indication ?
Does the engine get "primed" as when a carbureted engine has some fuel sprayed into the throttle body or directly into cylinders (I think) or in our case is the injection system just pressurized so the injectors will instantly squirt into the cylinders while starting? I'm not sure I really understand how the system works.
Clear Skies,
Gomer

[Don Nelson]

Since none of the experts have answered, here's mine, FWIW.

Many years ago I was taught, and my start check list reflects - throttles, props, and mixtures full forward on prime with pump. How long to prime depends on experience, (and whether cold or hot start), then throttle back to about a 1/2" if cold, again depending on experience in your particular aircraft.

Best, Don

[Zach Grant L1011jock]

It really matters not as the Bendix RSA is a metered fuel based on mass of air. Opening the throttle only marginally increases flow because the engine is not running and no air is flowing through the the servo to measure you are running in essentially the idle mixture setting. I say you can increase it marginally by going to full throttle as in a gal or two per hr. Going to full throttle may make he difference between a 10 sec prime and a 7sec prime...not much more.