The water pump works from the leisure
battery and not EHU. Howver when you are on EHU the
battery is connected to the charger and so tends to be at a good voltage. Sounds like your
battery isn't well charged and is poosibly on its way to the great
battery store in the sky. a) Check the fluid level in your leisure
battery; b) Get tthe
battery checked.
At least five possibilities
a) There isn't any grey water in there. Manually check (not using waste level indicator) Could be option "b"
b) You have had the valve open all the time and the waste has drained. You are closing the valve when you think you are opening it (been there got the T shirt)
c) MoHo isn't parked level. and drain is above waste level
d) Leak in waste tank or pipework. Fill waste tank and check underneath the MoHo
e) Waste pipework is clogged. Buy 6 litres of cheap own brand coke; Close the drain valve; Pour 2 litres down each sink and the shower; Drive for at least an hour; Open the drain valve.