PHP Built On Windows NT 2JFVL4J-LI 6.1 build 7600 (Windows 7 Business Edition) i586
Database Version 9.2.2
Database Collation Dutch_Netherlands.1252
PHP Version 5.4.7
Web Server Apache/2.4.3 (Win32) OpenSSL/1.0.1c PHP/5.4.7
WebServer to PHP Interface apache2handler
Joomla! Version Joomla! 3.0.2 Stable [ Ember ] 08-November-2012 14:00 GMT
Joomla! Platform Version Joomla Platform 12.2.0 Stable [ Neil Armstrong ] 21-September-2012 00:00 GMT

Adding the port to connection() solved the issue.

in libraries/joomla/database/driver/postgresql.php line insert at 72
$options['port'] = (isset($options['port'])) ? $options['port'] : '5432'; //Default PostgreSQL port 5432

in libraries/joomla/database/driver/postgresql.php line 116
$dsn = "host={$this->options['host']} port={$this->options['port']} dbname={$this->options['database']} user={$this->options['user']} password={$this->options['password']}";