There are no pulsations in 5 of the 6 injectors in my car

Good morning:

I have a problem with my car is a Chevy Monte Carlo 2002
Motor 3.4

For 3 months that no mechanic finds the fault to my car, the problem it has is that it only has pulsation in a single injector of the 6 that the car has but for that reason it does not start and the strange thing of the case is that if I leave for a period of 8 hrs the car's battery disconnected and at the time of connecting it I can do it I can do it, I can do it, I can Moment to try to turn it on again does not turn on again and return to make the same failure of the injectors' pulsations.
I would thank you if they could help me with the problem of my car.
Thank you