Jams and jellies have a ph in the lower part of the 3s, and not generally up near 4. According to the site I am linking to, the ph of jam and jelly is around 3.1 to 3.5.
Interestingly, this overlaps with things that you would really thing of as acidic - things like vinegar. Vinegar has a ph from 2.0 to 3.4.
The ph of jams and jellies comes largely from the fruits the jams and jellies are made from. Sugar has a ph around 5 to 6, but fruits like strawberries have phs around 2.3 to 3.