There is an easy do-it-yourself way to test your injectors & pump.
1- remove the injector from your engine.
2- hook the steel fuel line back up the the injector with the injector facing away from the engine.
3- Bleed the fuel system. http://www.hoyetractor.com/bleed.htm
4- turn the engine over and let the fuel spray out of the injector onto a piece of cardboard.
WARNING!!!!! the fuel leaves the injector at about 3,000 psi! The fuel spray will slice into your skin and, if diesel gets into your body, can KILL you! Dont ever let the fuel spray on you!
You are looking for a nice round mist pattern on the cardboard. If the fuel "squirts" or the pattern is irregular, you have problems & may need a new injector.
Not sure if it is the injector that is bad or the pump? Try a different injector or try the same injector on one of the other fuel lines.
Not getting any fuel out of the injector? READ - http://www.hoyetractor.com/support/knowledgebase.php?article=12