i dont think they fail unless theyre clogged..    the worst  thing you have
to worry about is the rubber seals leaking

In a message dated 10/24/2016 1:25:29 P.M. Eastern Daylight Time,
kkalnsf@GMAIL.COM writes:

We heard  from an  auto tech that fuel injectors have a service life of
about  70k to 80k miles before they start falling out of spec. And while
they may  not completely fail for many more miles, the best performance and
fuel  mileage would be achieved by replacing them no later than at  100k
miles.