[C320-list] Macerator Pump

[Colin Evans]

 My macerator pump won`t self prime.  I have to pour a couple of litres of
water dowm the pumpout deck fitting to get it started. I thought there would
be enough head of water in the holding tank to get it started
I`ve taken the vent off the holding tank as I though there may be a
blockage, but it made no difference. 
Once going it is no problem. It empties the tank okay
Any ideas.
*************************
Regards
Colin Evans
Watermark #774
Lake Macquarie, Australia