Put pears in a large saucepan; add enough water to just cover pears. Boil uncovered for 40 minutes, or until fruit is translucent. 

Strain juice through a double layer of cheesecloth or a jelly bag. Let drip slowly, do not squeeze bag. OR use a Steamer Juicer to extract juice.

Measure juice. For every cup of juice add 3/4 cup sugar. For every 3 cups juice add 1 box pectin powder. 

Add vanilla and bring to a boil stirring often. Boil until juice cannot be stirred down. 

Pour into hot sterile half-pint jars, wipe rim, seal with hot sterile lids and rings. Process in full boil water bath 10 minutes.