How to solve this problem?

[bluel78]

Looks like fish eyes caused from silicon or oil on the surface, in the air, or from your air compressor. You could spray some of your paint onto masking paper and if it fisheyes on paper you have an environment, or air compressor problem. If it passes the paper test sand smooth and clean with lots of hot water and dawn dish soap. Don't dry it using compressed air instead use a fan. Next wipe it down with mild prep solvent and paper towels. If you see the prep solvent move around on the surface repeat the above or use a heat gun to get the oil and silicon out of the pores of the metal. If you still have problems use lighter coats and try to get them to bridge over. The old days we used fish eye eliminator to the paint but it caused more problems than it fixed.