I believe that copper is generally a single flare. Not really the best thing for fuel, I would think.

Your trouble might be because of using a bubble flare instead of a double flare? Are you sure that the tank fitting is a flare, and not pipe thread?

Last edited by Norcal Dave; 08/13/2018 7:00 PM.

~ Dave
1950 Chevrolet 3600 3/4-ton with 261 engine & T5 Transmission