Fuel pressure Regulator was replaced a year ago, but if you mean leaky fuel injector then it will be difficult to pressure test, any how I will pour one injector cleaner tomorrow and will see if it cleans the injectors and valve seats so that any possible leak can be stopped, otherwise i will have to leave the car next week at service center so that early morning they will connect OBD II scanner and see the firing and fuel pressure etc.
thanks for your advice, this problem appeared after head gasket replacement job only otherwise it was fine before, may be they did some gunk cleaning from valve seats and now leak has started.
will update later.