Could you have reversed the suction/discharge lines when re-assembling?
That's why mine wouldn't work after initial installation! So Jeff beat me to it! To me, they are not intuitive. The outlet should be the inlet and vice versa, which is why I got them wrong ('cause I didn't read the directions)!
The suction tube, inside the tank, has a filter on its end. I suppose that could get clogged if enough gunk got into the tank. I've never done it, but I think you have to disassemble the tank to get at it.
You do not have to prime the pump. Did you try disconnecting the outlet side of the pump, at the pump (the tube that runs to the injector) to see if acid comes out of the pump at that point?
The pump tube is a consumable part. That should be replaced at least every other year, if not every year. Technically all the tubing are consumable parts, including the lines that run from pump to tank and pump to injector.
The injector can get used up, too. So that gets replaced periodically, too (though it sounds like that is not the problem).
If the pump is rotating, and acid does not flow from it when the outlet tube is disconnected, it pretty much can only be four things:
- the pump tube,
- the inline filter in the tank,
- a clog in the tube running into the pump,
- a clog in the tube that the inline filter is attached to