Now that I've read the post more slowly, I'll try again.
When you removed the injector pump, did you remove the shaft with the pump or leave it attached to the drive gear?
Did you make sure the pump timing marks were lined up before you removed the pump, as well as making sure the engine timing marks were in the right position?
You said you changed the timing? In what way did you change the timing? Did you rotate the injector pump in its slots or change the position of the drive gear?
Are you certain that the injector pump is turning?
You could have a broken shaft or a stripped gear in the timing gear train.
When you installed the rebuilt pump, did you remove the little window so you could see the timing marks inside the pump to make sure they were aligned?
If you left the shaft in the drive gear when you removed the pump, did you check the end of the shaft to make sure the "dot" on the shaft lined up with the "dot" inside the pump?
Did the pump rebuilder give you any indication he found something wrong with the pump that could have caused your initial problem?
Give us some more info and we'll help all we can.
Mark