It would really help if you could coherently describe setup and then describe the method you used to test it and then the problem you're seeing.
What you wrote above really doesn't make much sense AFAICT.
The fact that the cap is off of the waste pumpout deck fitting doesn't mean much...since the
holding tank is normally vented...
Is there a diverter valve in the deck pumpout fitting
line, that selects whether you're emptying the tank using the macerator or the deck fitting? If there isn't, there probably should be.
There should also be a ball valve or seacock between the macerator pump and the through-hull, since, if the hose fails, you won't have any way to quickly stop the water from coming into the boat and then your boat will sink.
Unless your
holding tank is below water level and uses a top-mounted pickup tube, the amount of vacuum pressure that the macerator
pump needs to generate is minimal, since gravity and air pressure will both be working to force the waste through the macerator
pump.
BTW, as Freesail points out, it is rather tacky and rude to post the same question multiple times to try and hasten a response. I'd highly recommend that you read the POST in my signature to get the most out of your time here on sailnet.
__________________
Sailingdog
Telstar 28
New England
You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.
—Cpt. Mal Reynolds, Serenity (edited)
If you're new to the Sailnet Forums... please read this
POST.
Still—DON'T READ THAT POST AGAIN.