In a large bowl, mix sugar, cinnamon, salt, ginger, nutmeg, and cloves. Add pumpkin, soy milk, and eggs; whisk until well blended. Pour mixture into unbaked pastry in pan.
Set pie on bottom rack of a 425° regular or convection oven. Bake for 15 minutes, then reduce temperature to 350°; continue baking until center of pie is set and a knife inserted in the middle comes out clean, about 45 minutes longer.
Set pie on a rack until cool, at least 2 hours. After serving, chill pie airtight.