The ecu controls the injector ground, NOT the + side, to lower the current handled. If all the injectors are open, it means a short in the wire from injector to ecu, or a short inside the ecu on the injector driver circuit.

If you can measure 12v (maybe 5v, probably 5v in fact) across the two injector terminals, that's the problem. Switch must be in run position. Also try it in start possition. There are two control loops in the ecu for the injectors. The ecu and ign get power from the FI relay in start different than in run. The ecu controls the fuel pump in run, but not in start. The ecu will kill the fuel pump in run position if the ecu does not see the tach signal from the coil.

Check the ecu for a fishy smell, which is a sign of leaking capacitors and ecu failure will closely follow, if it hasn't already...