water not working in mardon caravan?

i have just brought a mardon classic supreme very cheap. it has cleaned up well but i cant get the water system to work. the pump works and so does the water heater which does fill up but nothing out of the taps. could it be the microswitch? also the water heater was leaking out the bung and it had been patched up. have put new washer on and is fine but i think the system must of run dry at some time because the fuse for the water pump has burnt out and i had to bypass this to get power to the pump. could the burnt out switch has caused damage else where. would like to hear your ideas. thanks