Bmw x5 starting prob

[Simplesi21]

Hi everyone I have a problem with my x5 e53 3.0d 2003 it was running fine but then it started running rubbish, so had a look under the bonnet as a mechanic friend said to check the injectors, so took the air intake off started to undo the injectors replaced the copper seals on all 6 put it all back together as told but now I'm getting excessive air and fuel through the top of the injectors and car won't start.

Please can any help as I am totally lost!!

Cheers Simon.