Can something be done to get users like this to vote more? E.g.
Show them a message when they ask a question pointing out that they have not voted match on answers to other questions.
Sending them a friendly email from a modulator and/or show them the message when ever they use the site until they have dismissed it.
Show a “poor up voter” label on all questions they post.
I think people should be up voting at least trice the number of times they ask questions. Only people will a VERY poor upvoting record should be targeted