Consumer prices rose in March at their fastest pace in nearly nine years, an increase that may fuel inflation fears but that likely overstates the extent of the acceleration. The Consumer Price Index, a closely watched inflation measure, rose 0.6 percent in March from February, the Labor Department said Tuesday. That was up from February’s 0.4 percent increase, and a bit faster than economists’ expectations. Core inflation, which ignores volatile food and energy prices, rose 0.3 percent, up from 0.1 percent in February. Prices were up 2.6 percent from a year ago.