isuzu 41he1 rebuilt an want run just hits an shuts down?

hey guys, just helped my buddy rebuild his 04 npr truck, well it dropped a valve an tore the head an piston all to crap, so we did an inframe an replaced all liners an pistons an bearings,new head,new turbo, an replaced an injector that had got hit . put motor together an all went well till we tried to start it, basicly the motor hits once an shuts off, never really starts just kinda fires once then acts like it shuts off. I have had removed the timeing advance off the pump thinking it was a shut off solinod but it wasn't, it was the advance for starting, so to put it back ya had to send the pump to shop to get recalibrated , so sent pump off the replaced to motor, timed the motor to the 8 degrees an the pump to the long line on the timeing gear an when the pump is slid into place the 8 degree mark on pump lines up to match the cranks 8 degree. an my cam shaft is timed correct with the B mark on gear is lined up with the machined surface of the head . we ve gone in circles with this an cant find any locals around that can advise us on this matter. only thing we questioned dureing the build was witch way does the arrows point on the pistons,,, do they point to the front of the motor ( towards radiator) or towards the rear of the motor since all the timeing gears are driven from the rear, did Isuzu call the timeing gear end of the motor the front of the engine ,,, deutz (german made) motors call the rear of the motors the front, so was wandering did the Isuzu people do this too. I talked to a guy an he said that we put our pistons in faceing the the right way faceing forward towards the radiator. just spins an hits once an kinda falls out like ya cut the fuel off, even removed the fuel return line to make sure there wasn't any head pressure.

isuzu 41he1 rebuilt an want run just hits an shuts down?