Andrew, sorry to hear you are going thru my same ordeal!
I was getting concerned I was the only one finding these issues
Coincidental and as an update to my situation, I have bad news.
Since my last post, my plane has flown a little over 2 hours, during the initial tests, I'm glad to report that it fly's great, no "heavy wing" etc. Just a pleasure to fly.
Yesterday I went to the airport to update the Gamin databases, as I'm paranoid with the pumps, I tested them, pump #2 did not bring pressure!! Number 1 was fine, multiple tests, (battery charger on), etc. No joy.
Today I return with a meter, tested the voltage on both pumps, same, 13V, swapped the connectors to see if the problem would move, Nope.
During these test, pump #2, that did turn on and made some small noise (compared to the loud, working, pump #1) stopped making any sound, now it's completely dead.
Even more coincidence, today I received an email from Lockwood Aviation reporting that the last pumps I had returned did have a problem, they did not specify what type of problem or the root cause) that they will send me repaired ones.
With today's report from Andrew, I see that I'm not the only one affected, I think Rotax needs to get involved to see what is happening!!