there's a valve in the filter housing that is "supposed" to shut off fuel flow when you remove the filter. Sometimes the valve fails, gets algae on it and won't turn off. You can clean it or you can just get the whole filter assembly (housing and all) for a buck or two more than the filter element. They oftentimes get broken off of the frame/engine anyway. Has to be one of the top 500 selling Kubota parts.
Secondly, a shutoff valve wasn't included into the OE build. It could have been. Problem is, it can get hit by junk while mowing tall weeds, or just general tractoring debris, turns it off and it starves the engine. Engine dies, middle of nowhere, hot, hornets swarming you, then you have to get off the tractor and turn the valve back on, and bleed the fuel system (which is easy enough). It's just more stuff to potentially go wrong so they left it off.
the valve in the filter housing is kinda nice. One thing about it, if you know how to do it just right, you can change the filter and never have to bleed the fuel system. Trick here, is that when you are screwing the filter bowl back onto the housing, screw it on just until fuel flows into the bowl and stop, don't tighten it up all the way yet. Let it flow through the bowl, and let it leak out a little. Once no more bubbles leak out (just straight fuel) tighten it on up normally and go start the engine. Might get a sputter but that's about all I ever got in doing them that way. Similar with the ring-nut style filter housings that included a on-off valve (metal housing plastic cup), don't tighten it up right away after changing the filter, let fuel flow out of the filter housing until no more bubbles, then tighten it up-done. 99% of the time I never had to bleed them. As a tech you learn to do things to save time, and save the customer a dollar or two if at all possible. Well, until the boss comes along and says hey this is flat rate work, we're charging 1.5 hours regardless if it takes you 5 minutes or 5 weeks.
