The function of the fuel injector is to inject atomised fuel into the combustion chamber of the internal combustion engine. It should spray the fuel on regular or intermittent basis depending upon the requirements according to the choice of the users.
It might be out of order sometimes producing tak tak noise. The reasons for the same could be as follows-
1) It could be due to the either pre ignition issue or might be might be due to wrong choice of the fuel which could give rise to tak tak sound.
2) Sometimes direct dirt might have made inroads in the injector causing unusual sound. In that case, the component needs to dissolved in the gasoline to get rid of dust particles.
3) Watch the function of the injector in the running condition by removing the injector to ensure that the health condition of the injector. Clean the same if required and put the same in the assembly and still the sound is persistent, replace the same with the new one.
4) Sometimes, the needle is not sitting properly causing improper mixture formation with the fuel and air causing piston knock in the engine. Minor adjustment of the needle is required to align them to bring back the same in the working conditions.