17' Series 2011 Expanda toilet issue

May 26, 2017
Millicent South Australia
Gday everyone, Looking for help for my expanda toilet. I haven't used my van for about 6 mths & when checking van before trip, I found the toilet seems to have lost water suction from tank to toilet itself. The pump is working but no water comes out. I did leave some water in tank during storage as i usually do & drain/ refill before heading off & haven't had the problem before. Accessing the pump looks hard work. If I pressurise the tank with a hose & block off the other tank inlet with a finger , I can get water to flow for a few seconds until I stop pressure. Has anyone had this trouble before & if so how was it sorted ? Thanks Brett