Interesting SuggestionFinding nothing on the fuel pump cut out, I would lean towards the anti-theft system:
Anti-Theft Components for 2015 Ford Mustang | SouthFloridaFordParts
When you try to restart your vehicle after a fuel shutoff, the vehicle makes sure that various systems are safe to restart. Once your vehicle determines that the systems are safe, then the vehicle will allow you to restart.
Hey there new to the forum here, encountered the same issue, just knee airbag deployed, where is this switch located? , thanks.Agree, I Have started it at last, seems like it got some switch on starter, just in case if someone does not know or will face same issue. Ecoboost have switch for starter.