I just bought a 94 xp that has been sitting for a few years and will no longer start. I removed the fuel tank, cleaned it out, and put in new fuel. I replaced all the gray fuel lines and a few cracked oil lines. I rebuilt the carburetors and made sure the spark plugs were firing. The engine is free and it cranks fine, but will not start. It will run for a second and then stall when using starting fluid. Any ideas as to what the problem could be?