GM postpones diesel pickup engine

General Motors Corp.'s cash problems have snuffed out plans for a small diesel engine that would have improved the fuel efficiency of the company's light-duty pickup trucks. Citing the poor economy, the struggling automaker announced Wednesday that it is indefinitely postponing its plan to put a 4.5-liter Duramax V-8 diesel engine in the Chevrolet Silverado and GMC Sierra pickups next year.