Pump-out troubleshooting

[djangodog]

Our marina has individual pump out hookups at the slips which is a nice touch. I successfully pumped-out our holding tank about 2 months ago, everything went according to plan.

I attempted a second pump out about 3 weeks ago: primed the pump properly, it had suction, then once sticking the nozzle in the deck fitting, nothing was pumped out; the only thing going on was the sound of air entering the intake vent. My assumption was that the person we have clean our boat every couple of months had pumped it out without telling us (which was fine by me!) since everything was behaving as if the tank was empty.

Tried to pump out again this weekend in order to put some cleaning solution in the tank - same problem. Only air is being pulled into the intake vent and we know the tank isn't empty. Pretty sure there aren't valves on board to switch before pumping out - so it should definitely work.

Any ideas on what to check or what could be the cause? There's no 'head odor' so no obvious leaks. Thanks in advance...

[johnnyquest37]

Try plugging up the air vent so that suction can develop in your holding tank.

[Minnewaska]

In my unscientific observation, pump outs are entirely unreliable to actually empty your tank. I've had what I thought was a near full tank (77 gallons) take a minute to pump and just knew they didn't get it all. The most recent vindication was the marina having to replace their pump, as it wasn't generating enough suction.

I finally installed a SCAD tank monitor with a PVC tube solid state level probe. It works great and has no moving parts to fail. Now I know whether I've been emptied or not and how much capacity I have at any point.

It is also safe to be full of $hit again.

[travlineasy]

Nothing seems to make sense with this one. If air is being drawn through the vent, then vacuum is being applied to the discharge/pump-out hose. However, I have seen situations where the boat is leaning a bit, therefore creating sufficient angle of the tank so the contents are on the lower side of the tank and the pump-out hose is situated at the opposite end and merely drawing air. Check the location of the pump-out hose and be sure the boat is tilted toward the hose while pumping.

Good Luck,

Gary

[JimsCAL]

An air leak in the hose between the tank and pumpout connection could cause that. Check the hose clamps.