// Load the Feeds Source object.
    $importer_id = 'csv_file_importer';
    $csvfile_path='F:/ImportFile.csv';

    $source = feeds_source($importer_id);

    // Load the source fetcher config.
     $fetcher_config = $source->getConfigFor($source->importer->fetcher);
     $fetcher_config['source'] = $csvfile_path;
     $source->setConfigFor($source->importer->fetcher, $fetcher_config);
     $source->save();

    // Tweak the importer configuration, to enable "Process in the background".
    $config = array(  'process_in_background' => TRUE,);
    $source->importer->addConfig($config);
    $source->save();

    $source->startImport();