buzzing noise fuel pump?

Hello all. I'm new to this sight and love reading about all the different topics about Tacomas. I just purchased a 2011 tacoma sport v-6 4X4 and have a question. After my truck sits idle for a while and i start her up. i sometimes hear a whirrling or buzzing noise kind of like someone squeezing the triggeer on a drill for about 1 or 2 seconds from underneath my truck just behind my rear seats just as I start driving. It only lasts for a couple of seconds and doesn't continue as I drive. Only when I first take off. I was wondering if it could be a waterpump problem or is this normal. Thanks for your thoughts. Chuck

 

Turn the key on but not far enough to start, and listen. If you hear the same sound then it's the fuel pump. It's only bad when you DON'T hear it.