78 Cold Start Not Firing

[MikeyZee]

Hey all. My son and I just got his 72 with a 78 fuel injected motor running. One of the problems we are having is that the cold start injector is not firing. I tested it by running direct power to it and it does click and sprays gas. When I did this and cranked the motor over it fired right up. Previously the only way to get it to start was to spray some starting fluid in it.

I traced back the wiring and studied the diagrams and it shows that the leads run back to #21 and #4. These two wires also are connected to the thermotime switch according to the diagram and confirmed by a continuity tester. The problem seems to be completely wierd. One of the leads from the thermotime switch and cold start injector both come back to the #4 position of the ECU connector the other one comes back to the #21 position of the ECU connector. The #4 wire is confirmed to get power on start through the umbilical cord BY wire. The power also feeds to the cold start injector and the thermotime switch on start. The thing that is puzzling me is that the #21 position on the ECU connector has no pin on the ECU for it to terminate. The 2 ECU I have are a11-600-000 which is supposed to be the correct ECU. I also have another harness from a 78 and it is identical. Has anyone else noticed this? Do I somehow have the wrong ECU? I have checked to see if maybe there is a splice in the harness but there is not. Anyone have any insight or knowledge of how to get this working?

Thanks All!