Maybe try testing the fuel pressure? The pumps may be running but not creating enough pressure to crack the injectors, which take at least 60psi (I think)

Or maybe whatever gas was in there for the last two years went bad and gummed every injector or other part of the injection system(long shot)

Or maybe something with the ignition switch is disrupting power to the fuel pumps when you turn the key to "start" versus "on" (here's that voltage check you mentioned)

At the very least, if there was no stabilizer in that gas when it was parked, I would drain it somehow and put in fresh gas with techron or seafoam. Todays gas with ethanol in it does not last!

I'm no expert, but I hope this helps
Im sure others will chime in with plenty of ideas, this is a great forum!

-Chris

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Streetside: 1987 Mercedes 300E Petrol Blue/Green
2014 Ford Mustang Grabber Blue
1999 Ford Ranger Green

Dockside: 1968 Eltro 17
1985 Silverton 34C