There should be a constant 12 volts to each injector plug with the ignition turned on. The second wire to the injector is the ground, provided by the computer through the quad driver circuits. Check the injector plugs with a test light (one of the few places that tool is appropriate!) to see if the circuit can flow enough current to light up the bulb, then check for continuity all the way from the injector plug to the computer on the ground side. By momentarily grounding the return wire, the injector shouls squirt. Don't leave the wire grounded for longer than just a quick tap, as the injector windings won't stand a continuous circuit without burning out. If all that checks out OK, try swapping a known good computer into the circuit.
Jerry
