Having trouble finding the leak in my right fuel tank. Used the manometer method and the balloon. Have tape over the gas cap. I have sprayed the tank with soapy water, used a brush to brush on the soluton, and tried to listen/feel where air might be escaping. No luck. Has anyone pressurized the tank and set it in water, like a bathtub. Tires are done this way. My soap solution is 7 to 1 recommended by a plummer. When I use the manometer method, the water level starts going down immediately very slowly.