I can hear a distinct sucking or whistling sound coming from the back of my truck as soon as she turns over. I put it up on ramps tonight and traced the sound, it's coming from the area of the black thingy on top of my gas tank. Problem is, the F-ing thing is so far up in under the body of the truck I can't get at it to find where exactly the leak is. Do I have to drop the gas tank to get at it, take off the bed, cut a hole in the bed, or what? Any ideas guys? I wouldn't really worry about it, except it's causing hesitation under WOT at 60-70 mph, making it dangerous to pass on hiways!

Thanks!