The National Highway Traffic Safety Admin. begins a preliminary defect investigation intoCorp.'s new '96 minivans. NHTSA has at least five reports of fuel leaking into the vehicle's evaporative emissions control cannister and causing the engine to stall. Another minivan inquest is under way. This is an internal look at Chrysler vehicles with failed or faulty antilock brakes. It is focusing on leaky piston seals as the most likely source of the problems. Chrysler says it has narrowed the list of possible problems to the Bendix-10 antilock braking systems in use in about 254,000 minivans and 68,000 cars in the '90, '92 and '93 model years. In a separate action, Chrysler is recalling 20,000 of the '96 minivans to replace rear seat bolts that could break during a crash. The recall affects vehicles built between Oct. 5 and Nov. 5 at the Windsor, Ont., plant.