Romans;

Good info as always from George and others...I'd like to add some troubleshooting suggestions...

If you have one injector spraying, and its mate (the one which is in parallel electrically) not spraying, as it certainly should, that suggests either the dead INJ is internally open (unlikely, but not impossible) or not externally connected (check your connectors and connections) OR (maybe more likely) it is connected and the pintle of injector is not moving...maybe glued stuck by the same varnish from dried fuel, which in carburated fuel systems causes other problems (like clogging the fine carb passages of the lawn mower during the winter non-use period)...soak pintle end in Marvel Mystery Oil or carb cleaner or mineral spirits (also apply a few drops into the fuel feed end so that gummage is attacked from both sides) until free, and 3V (YES 3V NOT 12V !!) applied MOMENTARILY(!) to INJ, moves pintle with an audible click...USE APPROPRIATE FIRE PRECAUTIONS WITH IGNITABLES AND SPARKS to prevent a VERY BAD DAY in the garage).

That technique can also be used to correct and check the incontinent Cold-Start INJ.

Additional: I haven't tried this to verify techniques work, but here are a couple of suggestions for electrical checks of harness (in-situ) with which you can confirm each INJ connector is getting a pulse...check for trigger voltage by connecting an 1157 brake light bulb as a load instead of INJ...although it is only a short pulse and a 12V bulb, the filament inertia should stretch it out enough to be able to see...otherwise, connect and indicate INJ trigger pulse with an LED (the ultra-fast response is sure to display the short pulse, use current limiting resistor for 3V, value is not too critical)...an oscilloscope would of course be the best suited test equipment because the pulse width can actually be measured, but not everyone has one of these available...

FYI, I have temporarily plumbed an oil pressure gauge to the fuel rail during troubleshooting operations to get confidence in FP and FPReg, but it looks like you might be beyond that point already.

Good Hunting!