You could try using get_template_directory() instead of ABSPATH. If wp-content is not in it’s original location on production server that might solve your problem.
Mind the lack of trailing slash after get_template_directory():
$font = get_template_directory().'/ledboard.ttf';
...
file_put_contents(get_template_directory().'/img/'.$arrayFuels[$i].'.png', $data);