Getting all revisions of an entity with EntityFieldQuery
In this case, use db_select instead EntityFieldQuery to get all revisions from the revision table:

$result = db_select('your_entity_revision_table', 'yert')
    -&gt;fields('yert')
    -&gt;condition('entity_id', {your Entity ID})
    -&gt;execute()
    -&gt;fetchAllAssoc('revision_id');

kpr($result);