OK, so by looking up a wiring diagram for the 870 ECM, I see that it has two banks of fuel injector controls with 4 injectors on each bank.

My question is, at any given time what it the maximum current output on the signal wire the ECM uses to control the fuel injectors?

I'm not really too familiar with the injectors and am not sure whether the actual current to power the injectors is given over this lead coming from the ECM or whether It's just a control signal and the injectors draw their power direct.

Any ideas guys?

 

The injectors get their positive voltage source from the INJ1 and INJ2 fuses. The ECM switches the ground side of the circuit.

The power F540N N-channel FET transistor (one, not two) used in the '870 ECM is rated at a peak 130W dissipation, and a peak switching current at low frequency (20K) of 23A continuous at 14V nominal operating voltage.

If you need more current than that, consider installing an I-R power MOSFET external to the ECM on its own heat sink.