Originally Posted by Tom and Maje
Less than a week after we got the boat one of our toilets stopped working. The pump handle will initially pump, but then stops and won't depress to pump out the waste. I've had the tanks
pumped out, disassembled the pump, checked the lines, there are no apparent blockages. Does anyone have a clue as to what could be wrong? Tom
Sounds like a blocked tank vent. The vent provides an escape for air displaced by incoming waste...when the air can't get out, the system becomes pressurized, creating back pressure that makes the toilet increasingly harder to pump. The pressure can dissipate while the boat sits, allowing the toilet to pump normally for the first flush or two after you come back aboard...till it repressurizes. The vent also provides a source of air to replace tank contents as they're pumped out...when the vent becomes blocked, the pump pulls a vacuum that prevents it from removing more than a gallon or two. You've had it pumped out...but if the vent is blocked, the pumpout wouldn't have been able to get much, so your tank won't be empty.
Step 1. Open the deck
pumpout fitting to relieve any pressure.
Step 2. Using a screwdriver blade--or whatever works--clean out the tank vent thru-hull. If there's a screen
, knock it out...screens cause more problems than they solve.
Step 3. Remove the vent line from the tank and clean out that end of it AND the fitting on the tank.
If that doesn't cure your problem, the next most likely cause is mineral buildup in the toilet discharge hose that's all but completely blocked it.
If neither of those, the problem is prob'ly in the toilet. But my money
is on the tank vent.