John 146, before you go to removing you IP I would suggest some patience. You indicated you had fuel at the output of your IP but not at the end of the fuel line at the injectors.
You opened the bleed screw at the new filter and left it open until fuel ran out? Close that screw and go to the IP where the fuel line attaches. Open that bleed screw and let fuel drip. Tighten the screw after you get a good flow of fuel. During this procedure you do not need to turn the engine over. Just gravity doing the work! NOW BEFORE YOU DO THIS MAKE SURE YOU HAVE A GOOD FUEL SUPPLY IN YOU TANK
Next loosen the three nuts holding the fuel line onto the injectors. Now use your starter to turn the engine over. Have the throttle lever set for full throttle. Let engine spin for 30-40 seconds. Let engine set for 30 seconds (this lets the starter cool so you don't destroy it during your time of frustration). The another cycle of 30-40 seconds, wait another cycle. By the forth cycle you should see some fuel start to bleed from a line, then another then soon the third.
When you have fuel from all three lines tighten the nuts at the injectors. At this point your engine will ignite!
If you end up needing a IP do not send your to a shop. I can tell you where you can purchase a new one with out a core at about 1/2 what Kubota wants for one delivered to you door. You have to remove the two nuts and two studs at the top of the IP lift it out, replace the shims off your old pump onto you new pump and reinstall. I don't think your pump is kapoot just yet.