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Your injector is run by the yellow and red wire that goes from the ECU to the injector. The yellow wire is the injector driver and the red wire is the 12v battery circuit. On the 91 (so may be different on your car) these connections run from the green connector (pin #8 for the red wire and pin #17 for the yellow). Have you checked the continuity of these wires, from the ECU to the injector connector? Also note that a short in these wires will blow the injector driver in the ECU. The drivers are at the green plastic object in your photo above…normally listed as Q101 and Q102 or similar. While the photo above is not specific to that area, it’s difficult to tell if there is any damage there. ???
And confirm when you did Fordem’s suggestion above, about cranking the engine with the diagnostic jumper in place, did you leave the key in the on position, after cranking, to see if the code had changed??
 

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I’m not sure if the 1989/90 ECU will throw a code 42. From what I understand, it is possible for the engine to run with starter fluid, with the ECU completely disconnected, in these two years. IIRC, the ECU ‘monitors’ spark in these years, but doesn’t control it. That being said, the ECU should throw a code 41, if the ECU does not see the ignition signal. The first post here indicates that perhaps there is no longer a tach signal (tach needle not moving when cranking??). The tach signal is pulsing 12v to the ECU, and the ECU uses this signal to know when to pulse the injector.
 

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You seem to advise that you have no tach signal, or would like to test it. I don’t have the schematic for the ECU connectors for your car, but on the 91+ it is the yellow connector, at the #1 location (a yellow/blue wire). With the ignition in the on position, you should have 12v at this connector.
The brown/white wire at the noise suppressor is involved with the tach signal….with the ignition on, you should have 12v on the brown/white wire. If not there is an open on that wire. If yes then probe the brown wire at the suppressor. If no voltage there either, the suppressor is faulty.
 
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