I am having a strange issue. After engine shut down and ignition turn off i am hearing mechanical noise from the right side of the car fuel pump noise. The noise is extremely louad and continues until what i assume is when the spray rack regains fuel pressure. after that the noise goes away. I have no noise while driving. It only happens after the ignition is shut off. This mechanical noise is not the typical hiss of a fuel pump. This is not my first corvette, and have scowered the service manual to see if there is any mention of this problem. I only have 20k miles on this car. It is strange. I have no loss of power while driving and no hesitation while driving. At first I thought it may be a fuel filter issue due to the cars age and the lack of use. Thank you for any and all help..