Re: 2000 Mercury 25E hp
I don't know what equipment you currently have on hand. The starter operates off high current battery power. You need to connect the - terminal of your battery to the engine block and attach the red wire (+) to a high current switch. That switch is referred to as a starting solenoid. It has 2 large terminals, one receives the voltage from the battery, the other applies the voltage to the starter when it is closed. The starter also has a black wire between it and the engine block (ground).
To activate the switch (solenoid) you need 12v and ground on the small terminals on the switch. The power us usually applied through a spring loaded switch as you only want power to it when you are starting.
That's the basics.
Mark