If your vehicle is showing high-pitched whining noise from the back of the car or gas tank area, here are the most likely causes and the parts you'll need to fix each one.
The electric motor inside the fuel pump wears out over time, causing a loud, high-pitched whine directly from the gas tank area while the engine is running.
A heavily restricted fuel filter or in-tank strainer forces the fuel pump to work much harder, leading to a whining noise. This often happens if a new pump is installed without replacing the strainer or cleaning the tank.
Worn carrier bearings or low gear oil in the rear differential will cause a whine from the back of the car that changes pitch with vehicle speed, acceleration, or deceleration.
A worn rear wheel bearing produces a whining or humming noise from the rear wheels that gets louder with speed and typically changes pitch when changing lanes or turning.
A clogged vapor canister vent valve or a faulty gas cap can cause a whistling or whining noise as the fuel tank builds excessive vacuum while the engine runs.