Our new to us 2009 Kubota M9540 was a one owner tractor that was bought new and traded back in at the same dealer by its original owner. It only had 573 hours on it when I picked it up at the dealer. It was supposed to have been fully serviced and field ready. The engine oil filter and hydraulic filters look to be new. On its first trip down the road it would bog down and only run 8-10 MPH at wide open throttle in road gear. I could tell it wasn’t getting enough fuel. The see through fuel/water separator looked good inside and didn’t have any water in it, it’s easy to tell if it has water in the bowl with dyed off-road diesel fuel. The spin-on fuel filter is tucked away towards the rear of the hood and painted the same color as the engine from the factory, it’s very possible that they simply overlooked it and only cleaned the separator. I removed the factory fuel filter and replaced it with a Carquest 86393, made by Baldwin. The tractor will now run at almost 21 MPH on the road as it should and has a lot more power. The Kubota replacement fuel filter number is HH166-43560, the OEM filter is a little longer than the aftermarket filter that it crosses to. I suspect that the Baldwin/Carquest filter will do just fine, Kubota calls for a change every 400 hours. I can get the Carquest filters for around 1/2 of the price of OEM filters. I cut the factory filter open (582.3 hours) and found a slimy black layer coating the outside of the pleats. The inside of the pleats was the color of new filter paper.