High pitch noise from fuel tank area

My 1992 Buick Century V6 has developed a high pitched whine. The longer you drive the car the louder the noise gets.When you first start it's fine, then it seems as you brake the noise gets louder. There used to be what I would think is the sound of the fuel pump running for several seconds after the engine was turned off. But since I added Lucas fuel injector cleaner it went away. Any ideas?

I have a 98 Century and it is making a high pitch noise from the tank. It is definitely the fuel pump. I am not having any problems with the car but wonder if it means the pump is going out. Have you had problems with your since adding the fuel cleaner? thanks

[ I had a loud hum from my gas tank/fuel pump that went away when I open up the gas cap. I replaced the pump and has the same noise. I then trace the vacum for the gas tank to the charcoal canistor which had a nearly plugged intake . I drive many crappy miles. The engines vacuum is used to clear fuel vapors from the tank, and being plugged made a big vacuum in the tank straining the fuel pump. weird uh