could be over watering or over fertilizing, when trees get alot of nutrients sometimes they abandon fruit making in exchange for growth. is it getting new flushes of growth?

carambola are very profilic, i wouldnt be worried. the tree is probably still adjusting to its growing, fruiting seasonal cycles.

if you want fruit you can bend the branches until they snap a little. what this does (same principle as girdling)is prevent the flow of nutrients through the branch by breaking some of its strands when you bend it. what happens is the nutrients being delivered by the trunk to the branch ends builds up at the bend in the branch and it buds fruit.