Head pressure varies with the height or depth of the liquid.  But what do I know. 

It does, but not by much.  The head pressure might be around 0.33 psi at full tank and 0.11 at one third (when the issue starts)?  But the pump has to produce 44 psi.  Who knows, maybe the pump is ever so borderline in my case that a 0.22 psi loss (0.5%) matters?

Glad you got your bike fixed Max, go out and enjoy it. 

It isn't fixed, it is sitting in a shop for weeks waiting for parts while the weather has been fantastic

But I am hopeful!

There is now a filter/o-ring kit available    99999-0521

Experts?

Compared to me, for sure

Money grabbers I'd say since they want you money to run it in their dyno.

Perhaps, but I ran it by my master mechanic friend and he said what they did wasn't unreasonable.

The common experience of blocked suction screen is that it is worse as fuel level drops. This has been documented for 15 years or so.

I agree that the screen/pad is the most common problem when there are fuel delivery issues (that or the gas cap vent malfunctioning, which is the first thing they checked).  But nobody has explained to me a theory as to how the screen/pad can be the problem when the symptom is that the problem only occurs when the tank is more than half empty and gets worse as the level gets lower.  The weight of the gas in the tank is insignificant compared to the amount of pressure the pump has to make.  So if the screen is clogged, it should be clogged all the time, right?

Of course, as I said earlier, I don't know how it could be the pump in such situations, either.

The problem that the shop has is that Kawasaki only sell the pump for the C14, not any of the sub-assemblies (filters, o-rings, screens, etc.).
All of those parts that we use in our pumps when we DIY are for other vehicles even if they do fit the C14.
It could be the screen, or it could be a weak pump motor, or seizing bearings in the motor, or any one of 50 different things.
As with most modern vehicles the "solution" is to replace the suspected failing part and if that fixes the problem, move on to the next job.

The air-con compressor on my car has stopped compressing and I KNOW that the cause of the fault is the electronics in the compressor, but nobody will look at that. They only want to replace the compressor at great expense to me. Pretty much nobody troubleshoots down to component level these days as it is mostly cheaper to replace the whole unit than to take the time (time is money!) to troubleshoot the actual cause.

Max did you replace the pump filtet?

I am not able to do the fork seals, and they starting leaking like crazy again, so I had to take the bike in.  It seems they leak much worse when the weather is not cold.  Last time I investigated with the shop, they said they were several WEEKS behind.  So there was no sense leaving it with them.  And then the weather changed to cold and the leaking stopped, and so I procrastinated again.  I just threw the fuel starvation problem at them as well (what the hell) since they will have the bike and I would be without it, anyway.

They called and said their diagnosis after testing is that the fuel pump would not produce the correct pressure and has to be replaced (no mention of the "filter" pad being the issue).  I authorized it, but the part will take "7 to 10 working days", so now I have to sit and wait weeks

My problem with this, is that even if the pump were defective, as we discussed before, it should not matter the level of fuel in the tank.  And yet that greatly affects when the problem occurs.  So this diagnosis/solution doesn't explain that behavior.   But, I give up- they are the experts.  I guess we shall see.  Eventually....