I finally needed to replace my engine to my 1995 pathfinder 4X4 due to wear and numerous oil leaks. I installed a re-manufactured long block which comes with new timing belt, oil pump etc. and tested for leaks. I also replaced all fuel injectors and fuel pressure regulator and all necessary tune up pieces. The engine looks great but won't start up. I checked the ECU code and it gave a 55 code (no problem found). It has spark. How do I test for fuel being present at the combustion chamber? What is the fuel pressure at the injector rail? Help!