I found "looseness" at the lift pump connection too, same as your pic of the spring clamp (moved). So someone was working on your lift pump before you. All I could do in the limited access, was move the clamp closer to the bead.
Yeah that counterweight makes it very difficult to access the lift pump.
Here's how I accessed the lift pump. If you do what I did (in my pic) ---- you improve pump access "just a little", like 10%. If I saw your pic..... just
seeing your pic
.....I would have taken the counterweight off. I didn't have overhead lift, I would have to rig something, but it's difficult to self-lift the counterweight.
Try bypassing the water separator. I wiggled the water-separator fittings andit was feasible to let some air in there. They are press-fit. I took them out and re-sealed them.
As said above, I was able to "improve" the operation but in the limited time I had to work on it, I never solved the problem.
But to have that situation (injection pump sucking air in) suggests the lift pump was unable to supply the injection pump's flow requirements at full-power. So the air is an "indicator" that there's a vacuum in the supply - there should be NO VACUUM. The real problem is the injection pump is not receiving "positive pressure" from the lift pump. It could be a faulty lift pump or perhaps intermittent electrical supply.
