check just the point where the main CNG kit body (regulator) is present,,,,,there will be 2 cables there,,,one for CNG ,,other for Petrol,,,,,both shud be connected,,,,
if both are connected,,,,,open the carbeurator (the black round thing in the engine) remove the air filter and put very small quantity of petrol there in the center and then quickly start the engine with continuous pumping of the accelerator,,,,,,