Well I changed the filter and that fixed the issue but it was frustrating. Changing the filter was easy (other than I couldn't turn the fuel shut-off lever). I had an issue restarting the tractor so I tried bleeding the lines at the injectors. I started with #4 but only got a couple drops to come out. Then tried #3 and got nothing so I thought I had another issue. Farted around trying to figure things out but couldn't find anything so I went back to bleeding the lines again. When I tried to crack the line on #2 it felt like it was corroded to the line so I quit. When I cracked the line #1 injector it started bubbling like crazy. After about 10-15 seconds it started right up and ran like a champ. No idea why I got nothing out of the other injectors. Lesson learned anyway.