[v8volvo]

Thanks for moving those posts.

Back to the original question of a slight hang at ~3000 rpm:

I think the most important question is: is this a NEW issue that recently started, or has it done this all along? And can you feel it when you are driving, like it's a driveability problem? Or is it just something you can notice if you are carefully watching for it with the engine revving with no load, but makes no difference in the way the car drives?

Also, are you sure this is happening in the engine itself, not just in the tachometer? The old tachs in these cars often move with a bit of a jerky motion. What happens if you raise the revs more gradually than you did in that video? Does it still hit a sticky spot at 3k?

IMHO: as long as it doesn't present a problem in how the car drives, or represent a sudden new issue that is rapidly getting worse, then this might be one of those problems that's not worth putting too much worry into. The internal governor in the IP is a complex mechanism and there are lots of different ways it needs to respond to RPM, load, temperature/pressure, etc. What you are seeing might just be a fairly normal part of its operation, or close enough at least.

If there's no visible air in the fuel either entering or leaving the pump, and it has a good fuel filter on it, and the car's performance is still good and not detrimentally affected by this phenomenon, then I would probably just keep running it and see if the problem changes.

Could it run a little better/smoother/more evenly with a freshly rebuilt IP? Maybe yes. But it sounds to me like this issue is subtle enough to not be worth all that work and expense, at least not right now, as long as the IP is working fine otherwise (starts good, quiet, clean running etc) and not leaking.

The leaks from delivery valves (what you described as the nipple) at the pump head are common, since those valves often want to unscrew themselves when you take the fuel pipe off. Tightening them to their required torque in the IP head (can't recall but you can look it up), then the fuel delivery pipe to the valve with its required torque, should fix. The fuel pipes do crack every now and then. If you discover that's the reason for the leak, let me know, I have a box full of spare fuel delivery pipes and will send you one.