I have a 2656 diesel. It has all ways ran good but the other day it would only rev up to half throttle.
I changed both filters the first one was nasty, the second pretty clean. But didn’t help. I flushed the lines, then wound up draining / flushing the tank. It Was pretty bad. ( I don’t know the history of this tractor)
I also took the screen out of the pump it was clean. Then replaced the rubber hose from filter to pump. I have good flow of fuel to the pump. It will rev. All the way now but only runs a few seconds then slows till it dies. It sound good while running. I also took the fuel cap off the tank
iam at a loss about the only thing left is the pump.