The fields do not use the field name in the ID. For single fields, like a text field you would use $('#acf-field_1234567890abc') where the part after #acf- is the field key. This will work for any field that has a single input like a text, or number field. For others you may need to use something like $('[data-key="field_1234567890abc"] input') for fields like radio and checkbox fields.
The key here is that the fields use the field key and not the field name. Use and inspector like Firebug in Firefox to inspect what you’re trying to get.
