these new type fuel cutoff valves do not have filters on them up in the tank,
the old one's that came with the tractor many years ago did have screens up in the tank.
I ground down a short piece of copper tube and inserted it into the top of the fuel cut off valve so it stuck up about 1" off the bottom of the tank, just to help keep bad stuff out of the fuel inlet opening.
anything you can do to insure you have clean fuel is a must. also these old tractors do not like the new fuel, try to buy the old non ethanol fuel if possible.