Can't speak to the seal issue since I did mine a long time ago, but the injectors do indeed have +12V applied from the battery via the radio suppression relay, grounding through the ECU on each stroke. There is resistance inside the ECU. Mike suggested using a 10W light bulb to provide external resistance sufficient to limit the current draw through the injector and not burn up the windings. The voltage at the injector is irrelevant: as long as it is sufficient to operate it with frying the windings, then you're fine.