A diesel engine for the Ford F-150 light-duty pickup is looking dicey.

Ford had said it would sell a diesel F-150 beginning in 2010. Last spring, dealers were shown a 4.4-liter V-8 diesel said to deliver more power and torque than the F-150's 5.4-liter gasoline V-8 and offer a 20 percent fuel savings.

But last fall, with diesel and gasoline prices sliding from a summer peak above $4 per gallon, Ford officials said they would delay the introduction.

No new date has been scheduled, Mark Fields, Ford's president of the Americas, told Automotive News late last month.

"We're still looking at the appropriate time to do that," Fields said. "We've put it on the back burner for right now."

With gasoline prices around $2 a gallon -- lower than diesel fuel -- the business case for the diesel F-150 is diminished. General Motors and Chrysler LLC also have delayed diesel versions of their light-duty pickups, giving Ford less incentive to introduce the diesel F-150.

One industry source familiar with Ford's product plans said the diesel F-150 has officially been delayed until 2013. But it will likely be canceled outright unless diesel prices fall substantially below gasoline for a prolonged period, said the source, who didn't want to be identified.