1994 Honda Civic LX 1.5L

We've been having issues with starting a Civic.
Will not start when its raining or after a rain event.

During and after a rain event, check engine light stays on for a very long time (cannot hear the fuel pump priming) and doesn't turn off when turning the ignition (but not trying to start or crank car).
Car starts fine on warm days, with no rain. The check engine light turns on and off when turning ignition and the fuel pump buzzing sound is heard.

We have replaced the spark plugs wires, cap and rotor, fuel filter, and main relay.
All work was due anyway except for the main relay.
Replacing the above parts has not solved problem.

Do we have a problem with the ECM?

Is there a test that can be performed that will point to a bad ECM or a bad connection somewhere.
Again, issue is happening during and after a rain event.

Any advice is greatly appreciated.