2 wires to injector, one might be hot all the time, as they are usually ground side driven in the ECM, regardless probe both wires on injector harness plug) and you should see jumping on meter when cranking. (dont attempt to use a chassis ground- could hurt meter or hurt ECM)
the meter isnt fast enough so it will try to average and give you a garbage voltage reading but the point is that you are seeing a voltage pulse or just seeing a constant zero volts. A jumping meter or voltage pulse of any kind likely means the ECM is calling to open the injector properly.
while you have the injectors unplugged you could also check resistance between the two pins on each injector- should be something like 1.5, 4, or 12ohms. all should be same value around there. if any way high, way low, or open- bad time.