Steam pumpkin until barely tender, about 10 minutes (don’t let the pumpkin touch the boiling water or it will get mushy). Drain thoroughly and set aside.

In a saucepan, combine sugar, vinegar, cinnamon, and cloves and simmer, covered, for 20 minutes. Add pumpkin, return to a simmer, cover, and cook for 3 minutes more. Remove pan from heat and leave the pumpkin in the syrup; refrigerate for 24 hours.

Heat mixture to simmering and cook 5 minutes. Remove spices and pack pumpkin into sterilized jars. Fill with syrup. Seal and process 10 minutes in a boiling water bath.