In my Toyota Vitz 2007, I hear a sharp whining noise coming from the rear of the vehicle.
This noise does not always happen. When the vehicle is started, the noise is not there. But after driving for 15 - 20 minutes, the noise starts. The noise is more apparent when the car is stopped. Also, it gets reduced (sometimes stops) when in parking gear.
The problem seems to be similar to the problem described in this thread. The cause for the problem in that thread was the fuel pump.
My fuel pump got damaged during a cleanup and I had to replace the pump housing. The electric motor was not replaced. The noise was there before the replacement and the noise is still there.
What could be the cause of this noise?
If it is the fuel pump, do I have to replace it?