BOSTON (Reuters) - As gasoline prices vault to well over $3 a gallon in many parts of the United States, some gas retailers are turning customers away because their pumps can't be set above $3.

About 200 gas sellers in rural Vermont own pumps too old to compute the higher prices, state authorities said on Friday, causing some to shut their pumps when prices spiked above $3 after the devastation of Hurricane Katrina.

"I knew my pump was old but I didn't expect prices to rise this fast," said Bill MacDonald, owner of central Vermont's Waits River General Store, whose 25-year-old pumps can't display any price above $2.99 a gallon.

MacDonald kept selling below $3 until his pumps ran dry on Thursday and then briefly closed until authorities could find a solution. Another operator, Elmore Store, shut its antique pumps after facing the same problem.

Officials decided late on Thursday to allow retailers like MacDonald to cover up all price information and only display the number of gallons pumped.

They could advertise the price per gallon on roadside signs and then compute the charge face-to-face with customers, said David Lane, Vermont's Deputy Secretary for Agricultural Development.

¶ 5:23 PM