A friend has a 35 Ferguson tractor and asked for help. The tractor will start and run for perhaps a minute or so, then cut off, like it is out of gas. Wait 30 seconds, the engine starts up fine and will run for a minute or so, then cut off. The odd thing is the glass sediment bowl/fuel cutoff at the tank has a steady stream of air bubbles entering while the engine is running, they stop completely when the engine is not running. I made a remote gravity fed fuel cell and connected this directly to the copper fuel line to the carb, to eliminate any fuel tank/ sediment bowl issues. The engine started fine, and basically acted the same as before. The engine ran for a minute or so, then air bubbles started entering the remote fuel cell through the fuel line, and then the engine quit. Obviously this is a problem with the carb. I have not yet removed the fuel fitting at the carb and checked for a dirty screen, and have not yet sprayed the carb with cleaner and checked for leaks while the engine is running, but I will. Has any one experienced the air bubbles in the fuel line? or have any advice pertaining to the quitting issue? Thanks for any help. Seanelson