You are asking whether omitting a preposition from a phrasal verb makes any difference. Well, if you go by the definition, it mentions -
a phrase that consists of a verb with a preposition or adverb or both, the meaning of which is different from the meaning of its separate parts
While in most of the cases, it's true, in some cases, as in here, it makes no difference whatsoever.
I could find both usages.
to put some drink into a glass or cup from another container
Would you pour some water out for me, please?
This also means the same (without 'out')
‘Harry poured her a drink’ (note the objects though)
It's worth noting that on the same page, the entry 1.4 says that the phrasal verb is used more to express feelings.
pour something outwith object Express one's feelings in an unrestrained way.
‘in his letters, Edward poured out his hopes’
All in all, in some cases, omitting the adverb may not make any difference but it is highly recommended to look up some dictionaries before using it.