Editor box text is always blank

I'm trying to retrieve a value from an editor box when the focus changes using ajax.  I want to pull that text and send it as POST data to my handler.

@using (Html.BeginForm()) {
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true)<div class="editor-label">
        @Html.LabelFor(model => model.PipeSize)</div><div class="editor-field" id="PipeSize">
         @Html.EditorFor(model => model.PipeSize)</div>
}<script>$("#PipeSize").focusout(function () {
        updateData("ExitHeaderPipeConnSize", ($("#PipeSize").val()))
    });

    function updateData(field, numvalue) {
        $.ajax({
            url: "/Eval/UpdateData",
            type: 'Post',
            data: { fieldName: field, fieldValue: numvalue },
            success: function (data) {
                //do nothing for now
            },
            error: function () {
                alert("something seems wrong");
            }
        });
    }</script>

The UpdateData(string fieldName, string fieldValue) Handler inside the Controller updates the data fieldName properly.  But the fieldValue (the text from the editor box) always comes back blank.