If you have 12 volts on both wires to the top of the pump, then check to make sure the pump is turning by removing the oil filler in front of the pump and crank the engine while watching the gear. If you have voltage and it is turning, disconnect the injector lines at the injectors. If there is no fuel coming out while cranking, then the high pressure pump is failed. Thanks
Take the plate off the front of the shaft housing and then take the bolts out the gear. You will have to line up the gear marks to the camshaft gear and put the housing back on before you put the pump back on. Once the gear is back on and the housing is installed, the pump shaft will only fit in the gear one way. Then you line up the 2 scribe marks on the pump mounting flange and gear housing to time the pump. Be careful that you line up the correct mark on the camshaft gear, as the pump gear will have either a square or circle on it, the cam gear has 2 different marks as well, one for the crankshaft gear and the other for the pump. Just make sure the pump gear mark and the cam gear mark are the same and line them up.