Re: 1986 90HP Johnson will not fire
This engine must turn over at least 250 rpm when cranking to make enough current to fire the ignition. If the battery is weak, it may not be making enough rotational speed. Next, I'd disconnect the large red plug under the cowling. That will remove the key switch and control box from the engine wiring harness. Disconnect the plugwires. Then jumper 12 volts from the battery direct to the starter. See if you get spark from the plugwires as the engine turns over. The engine will spark/run without that harness connected. If you do, then you have some sort of short in the main wiring harness. Esp, check the key switch in the control box it-could be shorted out from rainwater.
