You may have found your problem already. One problem I had was with the pump. I replaced it because it would not work. I was using it on shore power. Now I have a replacement pump (in stock).
I guess the univolt was no suppling enough power to operate it properly. It would hum like it was working but did not. Worked when switched to battery. So now if I want to use the water pump, I use it on battery and keep the battery charged with a separate charger that I plug in when hooked to electric. Everything else works fine on shore power. This may work for you.