What causes your injectors to not get power on a 1990 Nissan 300zx?

Answer 1

To answer the question broadly, so long as you know that the problem is the injectors and not something else, i.e. lack of spark, there are several possible electrical reasons the injectors are not getting power:

• I am not an expert on the older Nissans, but the first items to check would be any fuses, circuit breakers, and/or relays in the circuit(s) containing the injectors. Should a relay be bad, the contact switch will not close, and electricity will not flow through the circuit, should a fuse be blown or a circuit breaker popped, no electricity will flow either.
• There could be a possible short to ground somewhere after the battery and before and switches, resistors, transistors, or the injectors themselves, causing the electricity to rout to a metal part of the vehicle before reaching the injectors.
• Check to see if any other circuits or electrical components are operating when they shouldn't, or if any circuits will not power down or turn off when they should. If this condition exists, then it is possible that the wires in the injectors' circuits are meshing with the wires of another circuit, causing the other circuit to operate improperly, and the injectors' curcuit to not have enough voltage to power them.
• Finally, be sure all resistors, transistors, switches, relays, etc. have the proper continuity or resistance.

If you know someone who is electrically inclined, have them check the circuitry with a DMM (digital multimeter), or have an automotive technician ASE certified in automotive electronics check it out.