Check the clutch pedal. there is a switch (plunger, press type) the clutch pedal lever presses in. Maybe its disconnected or disabled.
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My 3000gt starts without a clutch because it has remote start. If you have remote start then that is why.
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The galant plastic nipple that presses this clutch switch in from the level can become old, fall off, whatever.
I use a large zip thigh to replace this (just zip one in there and cut off the remainder. Why they didnt make a medal one or just kept the hole filled is beyond me.
Maybe this is what happened and the past owner disabled the switch. You cant drag race without a clutch safety switch, so keep that in mind.
You will understand what im talking about once you inspect your clutch pedal. If you dont see a white plastic part that could press the clutch switch, then its missing. Then you will only see a hole where something should go to press the clutch sensor in.
hell, maybe your switch is even missing.