I have had so much trouble with dirt from the tank that the tank got pulled and cleaned. Just work, but it is work. I put 2 filters in the fuel line. 1 between the tank and the fuel pump. 2 just in front of the Carburetor. Then came the "sticky" needle in the seat issues. 3 so far. Then, the power valve got sticky. All in one Carter B. So far my feeble mind has come up with, Residue from OLD gas melting from the new fuel and solvents. The thing is, persevere. It can be solved. My truck set for most of 20 years. The things that make it fun are the things I have figured out how to fix. Fix what you have. You will learn something. Keep at it, you will be surprised at how good it feels when it works. Clean, clean, and clean. I know that sounds boring, but it is funny what comes out of the oddest places. I have not run into the "Zinc coating" issues. We do have E 15 here and, it changes by season. But, so far, the issues are not the fuel by itself. Just time and neglect.