ST. PAUL, Minn. --- Minnesota, the first state to mandate the use of biodiesel, has temporarily suspended this requirement for 21 days while investigating why the fuel product is clogging fuel filters on some trucks, according to a report on Minnesota Public Radio. Back in 2002, state legislators voted to require that all diesel fuel sold in Minnesota contain at least 2 percent of the product made from soybeans. This law finally took effect in September after the state’s three biodiesel plants reached sufficient capacity. But reports of repeated filter plugging have state officials searching for answers. Gov. Tim Pawlenty, a major supporter of biodiesel and other alternative fuels, told the radio station that more testing was necessary in order to resolve the problem. Filter clogging seems to be present in certain trucks, in certain weather conditions. It’s uncertain whether the problem lies in the soybean-based product or in the diesel fuel it’s blended with. Further testing is expected to identify the source of the trouble.