1992 Lexus LS 400 battery runs down overnight....

hello. when i turn my car off at night, and wake up the next morning to start, battery doesn't have a charge. when i put a new battery in and turn the car off i hear a sound thats constantly running under the hood and does not stop, at the top of the motor, near the traction control. sounds as if gas is running to the fuel injectors or air is pumping from somewhere. if you all have any ideas, can you please help.

thanks, wilson