there are a few tests.
ohm meter. put meter on low range connect it to the injector.
it will read very near 12 ohms if not bad. it can read less or more ,or open.
open is infinity and will read just like not connected , holding probes to air .
always measure from 1 injector compared to others, if they all read the same, then all is well with the coils inside.
but that don't mean the injector is good.
it can be clogged or the pintle can be jammed. (no squits) sparks dry.
clogged is hardest to find.
jammed is easy too.
but before you do that make sure the DRIVER is working.
the driver is what we call the power transistor in the ECU that drives the Injector coil.
this transistor just acts as an electronic switch,
it grounds the injector to fire it.
the other side of all the injector coils are at 12v battery key on.
so the ECU fires them in parallel or in sequence depending on RPm.
ok, next is (easy to hard is best)
let do the NOID test.
whole 9 yards.
the first link shows the NOID lite kit, you can rent
the second is a simple light bulb that draws extremely low current and works perfectly, as a NOID lamp.
I unpugged my Injector conn. then plugged the lamp wires directly into the Injector conn on the Harness side (ecu drive side) then I crank and look, is it flashing.?
car starts, is it still flashing brightly.?
if it is flashing well, then most likely the ECU is GOOD
If not , the the ECU is bad , the ECU drive wire is bad, or there is no power to this injector feed plug, bad wires again. (fuse ain't blown, as the others work)
if you have NOID drive. then next get a mechanics stethoscope.
then listen to all injectors, if they all sound ok then #1 is clogged, at the front screens.
if the #1 is not clicking at all then the injector is jammed. (gunked up in side)
send it out to witchhunter.com for clean. $19 . ( fast too) near Seattle.
they can perform a miracle on these. (cept bad coils)
New injectors are serious bread.$$$
I presume you have checked compression on #1 and spark to #1 and both are good.