45870I have 8.4 Volts going in. Without the motor hooked up: the voltage range is from 0.0 to 8.4 volts. The problem, with the motor hooked up: The motor only turns on when the Pot is at 80% to 100% and the controlling voltage range is limited to 4.5V to 6Volts. How do I get the motor to turn on using the full range of the pot and control the voltage from 0 to 8 volts like I want?

Most d/c motors require more power to turn on then they do to stay running. What is your motor operating specifications ?