We have an 05 trailblazer (not ext) and found out the fuel filter is inside the gas tank. Big bummer as my husband can't change it himself. Dealer said they don't "Change" the filter so much as they clean all the fuel injectors. ??? I was confused about it. We have an 05 trailblazer (not ext) and found out the fuel filter is inside the gas tank. Big bummer as my husband can't change it himself. Dealer said they don't "Change" the filter so much as they clean all the fuel injectors. ??? I was confused about it.