12v conversion 59a starter solenoid 4 pole. 46 Mercury.

[JSeery]

Unless you have something different connected up the ignition switch should have nothing to do with the solenoid you installed. The ignition switch input should be hot all the time and connected to the same solenoid terminal as the battery (thus hot all the time, just like the original).

Might have to do a little more think here (that's on my part) but I don't see why it won't work the way you are wanting to wire it up.