Hi friends,
Thanks for your responses! I am not as mechanically inclined as my brother who owns the tractor but I am reaching out. To that end I don't know some of the more technical details or specific RPM #s.
I do use the tractor and have experienced the drop in RPM.
I don't know the hours. He bought the tractor in 2013 and feels that it is 'not that old'. It doesn't get used much in the winter, and just a few days a week in the summer depending on the weather, mowing mostly.
We always mow in 4WD, this is in Vermont.
Generally while mowing the tractor holds the 'mowing RPM' (which we are instructed to do, "Set it at ###, it should be fine.") in low, downhill and on the flats easily. On almost any incline (where you'd notice on a bike or walking) the motor slows down, as if it was receiving less fuel. The steeper the sooner, Our climb would take much longer than the other way. When we talked to my brother he'd tell us it was the stall guard kicking in because of the load (PTO & gravity).
This spring I was driving the tractor up a very mild incline, no mower, bucket empty. Put it in high (rabbit), crank up the throttle to 3/4s, 7/8s, put the pedal down, it should buzz right along. Indeed it would go up to ~ 18 MPH for about 30 feet then totally stall to a crawl. Obviously one throttles down, resets, and tries again. Same thing, so I end up going half throttle at half speed. Again my brother said it was the stall guard...
Until 'he' went mowing with the tractor. He tried every mode, high, low, HST, not HST, stall guard off or on. The tractor was dying on him on the mildest of uphill inclines.
He has recently talked to some folks himself and is going to try changing the fuel filters, and looking at the fuel line where apparently there is a 90-degree bend that might be collecting gunk.
I'm thinking it is the filters, I'm hoping so as that is an easy remedy.