It depends on how "weak." So long as you are posing an interesting question, the research is carefully done and error-free, the draft is well written, and you have some interesting results, the lack of many extensions, bells and whistles should not matter. If anything, you will get some good publicity. Some in the audience may take the information back to their home departments and say: "A grad student named Poulsen presented an interesting paper. He/she is on the job market and we should interview him/her." This will be more effective than just a routine application sent through the usual formal channels. And then, when your paper is improved by the time of the interview and fly-out, it will provide further evidence that you are an active mind and more than a one-off in research. It will be even better if the improvement is the result of feedback you got at the conference from some of the same people who are supporting you in their home departments; they will be doubly pleased and energetic in their efforts.