79. An operating diesel engine that suddenly loses power, is due to a/an __________.

A restricted turbocharger air intake immediately reduces air supply, causing a sudden loss of engine power. Diesel engine power depends on air supply; sudden power loss indicates an abrupt restriction or failure in the air or fuel supply. Low fuel viscosity, dribbling injectors, and oil leaks into the turbocharger cause gradual performance changes or damage, not a sudden power loss.