yap away vs yack away

yap away and yack away both are verbs.

Word	Noun	Adjective	Verb	Adverb
yap away	No	No	Yes	No
yack away	No	No	Yes	No

As verbs, yap away and yack away are synonyms defined as:

Other synonyms of yap away include jaw, rattle on, yack.

yap away (verb)	yack away (verb)
talk incessantly and tiresomely	talk incessantly and tiresomely