What I have seen in the past is that the same 12 volts turning on the fuel pump turns on the injectors. There are two things required to operate the injectors, or any circuit for that matter, in a vehicle. You need 12v and ground. The 12v is easy to confirm. Using a DVM, or digital voltmeter, with one lead connected to ground, check both connections at the injector. One should have 12v on it. If not, locate the source of the voltage ad trace to battery. Many vehicles use the ECM to control relays, a main for the voltages to the engine, and one for the fuel pump. Moving an engine from one vehicle to another can be tedious; it is necessary to be methodical and observant. Make no assumptions. Ray