On a Datsun 280zx there is a loud whining noise coming from the back passenger side is it the fuel pump and if so should i replace it or would it be caused by the fuel regulator?

A loud whining noise from the back passenger side of a Datsun 280ZX is likely indicative of an issue with the fuel pump, as these components are typically located in that area. However, it could also be related to the fuel pressure regulator or other fuel system components. To determine the exact cause, it's best to inspect the fuel pump for any signs of damage or wear and check the fuel pressure regulator for proper functionality. If the fuel pump is indeed the source of the noise and shows signs of failure, replacing it would be advisable.