and before it didn't works (the model was gray without the texture) because I had set, in Blender, the "Cycle Render"
Remember when you export the .x3d and the UV .jpg check to stay in "Blender Render"
I just discover your post and it is while I am dealing with colors not showing up in addition to geometries deformed and overlapping faces.
I am working new models in Blender Internal to validate this. It seems that the modifiers like solidify used under Cycles and then exported through vrml2 or x3d are really screwing up the models.
I am working on testing this and I will post results asap