1992 GMC Jimmy injector wiring

My information shows both the injectors get voltage from the same source.

You might try unplugging both connectors for the injector/s, then turn the key on, check for voltage at both plugs?

If there is still no voltage for the one injector, then you will need to backtrack the voltage feed for that one injector.

The voltage feed should be red for one injector and white for the other.