1998 Range Rover fuel pump

I had a new fuel pump put in and it now makes a whistling sound. I thought it was my a/c at first but its not. The mechanic told me that he mounted the fuel pump on the outside of the tank and that its normal. I think not. Is there any way to correct this problem short of buying a new fuel pump. Also, for some reason, the gas tank is now empty at 1/8 of a tank. Please advise. Thanks in advance.