Reply To: 1958 Johnson 50 hp

[Don]

You might try using bypassing all that stuff and using one 6 gallon tank with a known good fuel line.  There is some sort of issue with your fuel system if the engine runs well on a single 6 gallon tank.  Could be a restriction, air leak, or both.  These engines suck down alot of fuel, so a good fuel system is required.