Hello,
You can check ECU wiring from here:ECU wirings

As you have -92 model, it shall have L8 ECU. So here is few tips for you:
-Check pin 1, GND
-Check pin 19, GND
-Check pin 20, 12VDC,as I understood you don`t have power here, so check this:
"power to pin 20 is supplied with 12v by the fuel injection relay (m11) this relay also activates the fuel pump relay (m10) so if the pump is priming then the fuel injection relay is working" --> I`m not sure where this locates, but it`s either in main fuse box or clipped under the dash on the passenger side
Here is Relay locations, but not sure are these valid for Cosworth. If this is valid, relay what you are looking for is this, if M11 = XI:

If there is no power, I think issue is with ignition switch

-Fuel pump relay doesn`t have +12VDC feed from ECU. +12VDC is directly from battery trough fuses, so check fuses and measure fuel pump relay +12VDC terminals. (Fuel pump relays are +12VDC controlled from ignition switch)



-Check ignition switch, maybe this is broken
1) Ensure ignition is OFF.
2) Remove rear of ecu plug cover and insert plug back into ecu.
3) Turn ignition back on (do not start engine)
4) MAIN POWER CHECK: Check for DC voltage of at least 11.5V between ecu pins 19 and 20

or check relay I (Steering and ignition lock) -->see from Relay locations

Hope these help