OK, I have located the problem, which was a small logical error in the TANKPUMP warning light function. I have fixed it and will issue a patch later today.
If the alternator goes offline with the engine running, ELFEL should be lit but TANKPUMP will only be lit if the drop tanks are empty or if the external fuel valve is closed. With external fuel available, the fuel pressure will be high enough without the pump and there will be no warning. If the engine is NOT running, there is of course no fuel pressure and so TANKPUMP should be lit regardless. I had overlooked that part in the code.
Thank you for your help! /Tom