2001 500 HO sat for 3 years.

So…… 1. Drained oil, and got water out, 2. Replaced card with new, 3. Replaced cam and rocker (prob. Original problem), 4. Compression test 90 lbs., 5.spark yes with black kill wire removed. Now when I try to start the best I’ve gotten is backfire through card with pretty little fire. Fuel pump doesn’t seem to be working as I’ve tried to manually work it with vaccum but shouldn’t keep it from starting as carb bowel is full from gravity feed.