Running portable generator off vehicle fuel tank.

I am not a mechanic, the only experience I had was when I had my gas tank cleaned and lined. I had the tank bolted in and most of the hoses hooked up. Took a break and when I came back out gas was coming out of one of the small lines that was not hooked up. I removed the gas cap releasing the pressure and the gas stopped flowing. I had put about 5 gallons of gas in the tank to check for leaks.