Rumi began his involvement in Formula Onemotor racing when he sponsored fellow countryman Piercarlo Ghinzani. In 1990, Rumi bought the Osella team and renamed the team Fondmetal the following year. Fondmetal was shut down at the end of 1992 due to the high costs of running the team. However, the company remained in Formula One by leasing out their own wind tunnel to other competitors. In 1996, Rumi returned to the position of a team owner when he was a member of a consortium which brought Minardi and became the team's majority shareholder in 1997. At the end of 2000, Rumi sold his shares in Minardi to the Pan-American Sports Network who sponsored their driver Gastón Mazzacane who later sold the team to Australian businessman Paul Stoddart.