john deere 310se

I am new to this forum, I have a JD310SE that does not start. Battery and starter very strong. Changed fuel filter, drained fuel tank , replenish with fresh diesel, pump priming lever with filter valve open, pumps strong, fill a cup in a few strokes, close the drain valve, can feel pressure...

I have two JD310SE backhoes, one has about 3000hrs the other has about 4000hrs, both smoke under compression. No smoke under load. Both started to smoke at about 2000hrs. Traveling down hill under compression the tractors smoke but when you get back on the throttle the smoke clears up. Does not...