Timing is everything, and there are two sources of timing miscues for most diesels: the cam timing (skipped chain, broken gear) and the injection timing (could be shaft, gear, or chain, assuming not electronic injection!)
So your pump could be fine, but not spurting at the proper moment, or the injection system could be dandy, but the valves could possibly be out of time, in which case things still wouldn't work. If ether doesn't work, I'm a bit suspect about the pump being bad, as we've always gotten a few chugs out of starting fluid!
