Cipriani suffered a serious ankle injury in May 2008
Will Carling has scrapped plans to manage Danny Cipriani because he felt the Wasps fly-half was not focused enough about playing for England.
Carling hoped to help Cipriani, 22, get his international career back on track and the pair spent six weeks in talks.
But the ex-England captain wrote on his blog at Rucku.com: "I don't believe his focus is on playing for England.
"His desire to earn that shirt is not as strong as I want it to be and as strong as it needs to be."
Cipriani won his last England cap as a substitute against New Zealand in the 2008 autumn internationals, since when his representative appearances have been restricted to the second-string Saxons.
His Wasps contract expires in the summer and the club will announce next week whether he features in their plans for next season.
Cipriani has reportedly been in contact with the new Super 15 franchise Melbourne Rebels, a move that would halt his international career.
And Carling fears the Londoner could become one of English rugby's great wasted talents.
"The reason the whole concept appealed to me was that I believed here was a guy with a special talent, who desperately wanted to play for England, and maybe I could help him work things through with Wasps and England, as I know the key personnel in both camps," he wrote.
"I have spent the last six weeks trying to focus Danny and, without laying the blame at anyone's door, the main reason that I have decided not to go ahead is that I do not believe that Danny's focus is on playing for England.
"That and that alone was my main motivation for getting involved with him. It is not about money and certainly not about profile, it was about helping him earn the England number 10 shirt.
"And, rightly or wrongly, I have concluded that his desire to earn that shirt is not as strong as I want it to be and as strong as it needs to be."
Carling consulted England manager Martin Johnson, Wasps head coach Shaun Edwards and former internationals Josh Lewsey and Matt Dawson during the process.
Johnson told Carling that, despite speculation of a fall-out, he has not written Cipriani off.
Carling added: "I sincerely hope that it is not a talent that is never fulfilled in an England shirt but I worry that might be the case.
"I just hope that sometime soon Danny focuses on England and the hard work that will be necessary to earn his place in the team."