It all started to go bad when I replaced the fuel pump that would not stop running on, and on.
The pump kept running or the unit would not shut off?
Either way replacing the fuel pump would not have solved the original problem. Fuel pump would only stay ON because Control Board told it to.
Did you use a stock Onan replacement fuel pump of an automotive replacement pump? If automotive, is it only 3 to 4 psi? Anything greater will flood the carburator.
When you say "4KY D", Do you mean 4KY Spec D?
KY Service Manual:
Read the Control portion (Section 7) first to learn how things work. Then go to the Troubleshooting portion (Section 6) to isolate the problem (Initially it sounds like bad control board). The schematic (wiring diagram) for a Spec D version is on page 12-3 & 4.