Hi Sony,

That's not an easy one to answer remotely, and I suggest you bring the car back to the garage you had the work done to have it checked out. My first thought is that the timing, probably of the fuel pump, is out by a tooth, but perhaps the tension is too high as well. Presumably a new tensioner was fitted. If a new tensioner was not fitted, it could be binding and attempting to slow down the belt, which would be disastrous, as it could cause belt failure. 

Have it checked as soon as possible anyway.