Key won't start car?

sounds like you forgot to hook up the "trigger" wire which comes from the ignition switch through your clutch safety switch/neutral safety switch. It's the little red wire that plugs onto the screw at the top of your starter solonoid.

The User is right on - ignition interlock device is not up to par.

you can check for 12 volts at the little trigger wire (slides onto a machine stud shank) and trace backwards.

now if you touch the slide-on connector to the hot side of the starter solenoid and it does not start, that suggests the solenoid (or interlock device) is at fault. right now you are bypassing the solenoid altogether.

good luck.