thanks

Brown/Red and Red wired connector is for CDI power and fuel pump safety switch.
It stops the fuel pump from running unless you bypass the fuel pump relay or lift the metering plate plunger. (Sounds like it is functioning correctly.)

The black plug is for a remote Voltage regulator, may be an internal VR so not used.

The yellow/black with brown is likely the heater blower motor connector.

White connectors......
 

Connect the two (2) white plastic connectors with red and brown wires. Disregard the black connector for the voltage regulator. The '81 SC engines has the integrated VR in the alternator (new version) and don't use the external VR plug anymore.

Tony

Actually, it wasn't until '82 that the SC had an internal reg alt. Just check for an allen
slot in the alt shaft and maybe it's been updated with the later alt (junk).

Fuse or relay under the dash. Spray some kwik start into the intake and crank it. If it tries to start, it's the pump. CIS fuel injection is all about fuel pressure. You may need some gauges.