I had a leak last month. I removed the fuel and took the tank to McCarty Radiator in northeast Houston. They specialize in cleaning and repairing fuel tanks. They used some type of very hot chemical to clean the inside, then they pressured the tank to isolate the leak. They re-welded the tank and re-checked it. I watched TV in the waiting room for 1 1/2 hrs. $160 cash and I was out the door. We have a 22 gallon aluminum fuel tank. I also cleaned the pick-up tube and replaced the hose from the tank to the racor filter. I then changed the racor, and filter on the engine. So far so good. I'm no expert by any means, but you may be getting air in the fuel line.