SQL query problem

Hello,
I'm in the middle of the migration process from MySQL to PostgreSQL and
I cannot understand why this query isn't working (in MySQL it's working
fine). PG returns: ERROR:  Relation "_con" does not exist

This is my query:

SELECT
  _CON.con_id,
  _MOD.mod_ty,
  _VER.version,
  _YEA.year,
  _CON.dri_id,
  _CON.man_cod,
  _ENG.eng_pow
FROM
  db_data.mda_mod _MOD,
  db_data.mda_mod_con _CON,
  db_data.mda_mak_eng _ENG,
  db_data.set_mda_fue _FUE
  LEFT JOIN db_data.mda_mod_ver _VER ON _VER.ver_id = _CON.ver_id
  LEFT JOIN db_data.mda_mod_yea _YEA ON _YEA.yea_id = _CON.yea_id
WHERE
  _MOD.mod_id = '283' AND
  _CON.mod_id = _MOD.mod_id AND
  _CON.psd <= NOW() AND
  _CON.ped > NOW() AND
  _ENG.eng_id = _CON.eng_id AND
  _ENG.eng_fue = _FUE.fue_id


I will be appreciated for you help.

ML