Actually Ifixplanes, yes I would like that in the FCOM. Understanding something is much easier than trying to drill little bits of loose information in ones brain.
This dumbing down of the FCOM really does nothing for understanding the aircraft systems.
Thanks for the info!
The reason I associated it with the test, is that I have heard the same thing develop after a single engine taxiout where I was paxing. The PTU started to run slightly before the second engine start, then stopped for a bit during the start, and then started and did not stop before being airborne.
So knowing the procedures, I know that the PTU will have engaged after switching off the yellow elec pump before engine 2 start.
And I associated the second run of the PTU with the test during the 2nd engine start.
For me there is no logical explanation, unless there was some kind of unstable pressure delivered from the yellow edp.