Mazda Motor Corp. recalled tens of thousands of sedans and sports coupes to replace a fuel system that could allow fumes to pollute the air. The company also issued a recall notice for a second problem involving its new model 2000 MPV minivans, this time for a door latch that could open unexpectedly. The fuel system recall is for 172,154 of the model 626 sedans and MX-6 sport coupes sold between 1995 and 1997. The models have a fuel filler pipe assembly that improperly seals the evaporative emissions system. Owners can take their cars to an authorized dealer to be fitted with a sealing gas cap for free. Although the problem is not a safety hazard, motorists who fail to correct it might be unable to renew their vehicle registrations in some states because of pollution-control requirements, said Brian Betz, a spokesman for Irvine-based Mazda North American Operations.