You accidentally left your gas cap off in rainy weather. Or the gas station you fueled up at has a bad water filter and delivered you a slug of water with your Fuel. It's probably not condensation, since most vehicle fuel tanks are sealed systems not prone to water condensate like large fuel storage tanks can be. Wherever it came from, water in your gas Tank is a serious problem that needs to be addressed immediately.
This post first appeared on The Bell Performance Blog: Information For Fuel Co, please read the originial post: here