James, who won the last of his 35 England caps under Eriksson, was dropped from the international squad by new boss Steve McClaren.
But James, 36, insists: "I am still a big fan of Mr Eriksson and I think he will do City very well.
"At club level I don't think you can question his ability. The international scene is a completely different thing. He is a manager and he backs his judgement.
"When new players come in and are unfamiliar to everybody it is just a question of how quickly they gel. It is the same with us at Portsmouth.
"We've signed a lot of quality this season and provided we work hard and maximise what we have we will do well again."