Farmtrac 535 making a loud knocking noise from injection pump

[Hollis]

My farmtrac 535 was making a loud knocking noise coming from the injection pump. I figured the pump was bad so i replaced it with another one and set the timing back right. now the new pump is making the same noise as the other one but it is not as loud yet. anyone know what this could be?

 

[Frydaddy]

Did you ever find out what was causing this? I have just replaced two pumps on two farm tracs and have came up with the same problem on both. The loud clicking/knocking noise