After about 30 minutes of driving I can hear a loud high pitched whine that sounds like it is coming from the passenger side fuel tank. It seems to be electrical because it oscillates when the blinkers are on and when the A/C compressor engages or when the radiator fans come on. The whine stops the instant the key is shut off. I can feel a high pitched vibration that feels to be the same pitch as the noise when I touch the passenger side rocker panel directly in front of the rear wheel. Does this sound like the fuel pump is going bad or could it be an electrical problem like a bad connection somewhere? This started after having the 30,000 mile engine out service performed in December. I had the fuel guage sending unit replaced so that the guage would start working again.