If your injectors were large enough and the duty cycle went to 100%, you'd know you were out of fuel just by watching that. Had a friend send me a log from a sniper where it fell on its face at the drag strip and the injectors were at 100%. As I suspected the fuel system was not a good design (external pump mounted above the bottom of the tank, no return line, pulling through the stock sender). Having a properly designed fuel system is extremely important for any EFI system. If you didn't already have anything I would have gone in tank pump (like the Aeromotive drop in Phantom Dual 450 – Aeromotive, Inc ) if you were worried about it. I have the single Phantom 340 setup and it's been flawless since 2015.
Really it depends on what pressure the injectors were flow rated at. The industry standard is 43.3 psi or something like that but some companies fudge the pressure to make themselves look better.
Roughly 300 kPa, but you have to watch now because the newer vehicles like LS engines have 400 kPa/58 PSI rated injectors. Most injectors you can buy now (especially the thinner ones with plastic bodies like I run) would be fine to run at 58 psi line pressure if you were running out of headroom and needed some additional flow.
