Purchased a Ford 3000 Gas burner approx 72 model that needs a good bit of work. Have re wired and will turn over but not crank. Has spark at plugs and compression. When I pull the throttle lever to give it fuel the throttle rod moves but the governor arm does not. It does not move throttle on carb at all. Removed the throttle rod with spring per manual and it is adjusted at the proper length for the bell crank I have. Head was rebuilt on tractor before I bought it. Also when attempting to crank it backfires through bottom of carb. I am guessing this has something to do with too much fuel. Carb has been gone through and cleaned but not rebuilt. Any advice?