Where is the crank shaft position sensor on a 1995 Chevy lumina 3.1?

The crankshaft position sensor (CKP sensor) on a 1995 Chevy Lumina 3.1L is located on the passenger side (right side) of the engine block, near the front of the engine, and points towards the crankshaft pulley. It's usually mounted fairly low, close to the oil pan.

You'll likely need to look underneath the car for the best view. Be aware of hot engine components if the engine is recently running. A shop manual specific to your year and model Lumina would be the best resource for a precise location and detailed removal instructions.