View Full Version : Black water tank issues

07-16-2006, 03:25 PM
We have a Sun Voyager that supposed have a 40 gallon black water tank. We just camped for 2 days (2 of us) and the black water gauge read full within 48 hours and we used the campground restrooms part of the time. We have complained to our dealer numerous times and can't get any satisfaction. After we just dumped, it still read 1/3 full. I did see some posts saying some of these tanks are much smaller than the brochures claim. Also, my husband claims that the kitchen sink dumps into the black water tank. Would Gulfstream ever be so foolish as to design that? I'm getting to the point where I only feel safe camping where we have full hookups. Any other Sun Voyager owers have this problem?

07-16-2006, 04:20 PM
Are you SURE the tank was really full?

Those tank-gauges are notoriously-inaccurate, especially the black-water one. All kinds of .....uuuhhhh... "stuff" .... gets stuck to the sides of the tank and to the sensors during usage and causes them to read inaccurate. There's a lot of different home-remedies and various 'fool-proof' solutions to solving the problem, but I found that just keeping track of usage is just as good.

I also use one of those sprayers that you stick down the toilet and it sprays a jet of water all around inside, seems to do well (for me).

As far as the sink being connected to the black-water tank, I've heard of some rv's being made that way before but don't know if it's true. Easiest way is to open the gray-water tank outlet and run the sink. If water doesn't come out, he was right. Would GS do that? Wouldn't surprise me a bit!


07-16-2006, 08:20 PM
As was mentioned the gauges are not accurate because of toilet paper and other things being stuck to the sensors.

Also, most people don't realize it and the dealers do not tell the new owners that one should hold the button in for a while sometimes up to a couple of minutes for the low current to dry off the sensors, then you will get a more accurate reading as long as material is not shorting out the sensors in the tank.

I have heard of the bathroom sink and shower being connected to the black tank, but haven't heard of any manufacturer doing that for many years. Never the kitchen sink. :shock:

The best way to check is to open the gray water dump valve, then run water in the kitchen, after you verify that water comes out while running it in, do the same for the bathroom sink and shower. That way you will know what is connected to which tank.

You probably do have a 40 gallon black tank, just the good old inaccurate sensors giving you false information. I know ours does a lot of the time when we are using the toilet in the coach.


07-18-2006, 02:43 PM
Our bathroom sink runs into the black water tank. this adds needed water to help flush out the solids. We have a 75 gal. black and gray tanks. Our gages are never right. We have had five rigs with gages on the tanks and they have never been right. Had one service person tell us the black water sinceres are right under the toilet so they are alway wet.

07-25-2006, 05:09 PM
We have confirmed that our kitchen sink does dump into the black water tank and that probably explains most of our problems (other than the fact that the sensors probably don't work correct too). I guess at this point there is nothing we can do but I wish there was. How could Gulfstream be so crazy?


08-12-2006, 09:43 AM
Two comments I can add. One, I have looked at my black tank (actually, all three of my tanks) and the sensors are located in odd areas. For example, the "full" sensor is located probably 3" from the top of the tanks. I too was having my black tank read full within a very quick time, but in reality, the tank is not full.

Second, my black tank frequently reads full even after I empty it. As was stated, if something is touching the sensor (like toilet paper), it will trigger that light. I no longer put much faith in my guages...

08-13-2006, 07:27 PM
We, too, have a Sun Voyager with similar reading problems as you do. After dumping, connect the garden hose to the outside line leading into the tanks. Close the black tank valve and fill with a lot of water. Empty. Repeat process. Then keep the valve open a run the water into the tank. It will spray into the tank. This usually does it for me. Also, we just returned from NY State and traveled with a few gallons in each tank. Boy, did it clean out the black! I'm also assuming that your rig has the water line into the tanks so you can work from the outside.

08-14-2006, 04:45 PM
NEVER NEVER, run without water in the tanks. Heat will dry any solids

and ALWAYS seems to wind up on the sensors. When you have full

hook ups always keep the black closed so the liquids will help keep the

solids soft. Limit the amount of TP. We find that SINGLE PLY dissolves

better than "so-called" RV tissue. Add a few gallons of water and your

chemical and "head down the road". Not a perfect cure, but it helps.

Best Regards, Clyde

08-16-2006, 07:36 PM
My tanks are also 40 gals. US. My sensors also fail to be accurate, but I know that is not at all unusual. My bathroom sink is connected to the black tank but not the kitchen sink. I routinely get 5-7 days when dry camping and we do that a lot. It is indeed odd that your kitchen sink is connected to the black tank. The black tank flush system really helps to keep the black tank sensors working okay.

08-16-2006, 07:51 PM
According to FMCA the black tank cannot be connected to the grey water drains for the RV Manufacture to conform to RV Codes and Standards.
I have not found out whether these are the RVIA codes or what.

But I will continue to search for the RV Codes and Standards that were referenced by FMCA.


10-16-2006, 12:42 PM
After emptying the black tank at the last campground, it read empty there but a third here at home. Didn't use it at all on the way home.

Now that we are getting ready for winter, Chuck ran a little water through the tank to get the sensor to read correct. After about 20 buckets of black gunky water the black tank seems to be clear. YUK!!!!!

Something is definetely wrong. Where did all this stuff come from. Isn't there a back flush system that is supposed to clean most of it out? He got a lot of excerise carrying those buckets into the house to dump. I still say the old fashion way with running a hose down the toilet is the best rather than relying on these new systems.


10-17-2006, 01:26 PM

I don't believe the "backflush" is really a backflush. I believe water merely flows into the tank at the top of the tank (curbside). Because the tank floor is sloped downward, toward the drain, it runs down, presumably carring any "matter" with it. There may be some spraying action, but nothing like spraying it directly with a garden hose.

I'm getting the impression that on some MH units, the toilet pipe enters the black tank & gets close enough to the floor of the tank that solids/paper can build up against the pipe & not be emptied at the dump station. This sounds like what happened to you.

Solution: ? Take a rough road home & dump at a facility near your home? If you are dumping & don't have a line of people behind you: Close the dump valve and significantly fill the black tank with water thru the "backflush" spray. Then open the drain. I know the next comment - who wants to spend longer than necessary there? Certainly NOT me!

That amount of "black, gunky" water seems like an aweful lot, though admittidly, with normal use of the plastic hose, I never see the rinse water condition ... nor do I desire to! Ha Ha Ha.

10-17-2006, 02:36 PM
We are now getting a clear elbow. Always wondered why people had those. Going to "watch" until the water is clear. Now, won't that be entertaining. :o I won't be doing the watching. :D I'll have a bucket inside with soapy water. Chuck will yell at me when to pour it down.

I wonder if this had been a rental unit and when we bought it we got it partially furnished ???? :oops:


10-17-2006, 02:46 PM
We have a clear section that I use to see when clear water is coming out during the flush. Surprising what comes out after closing the valve and filling the tank part way with the flush then opening the dump valve.

Nope, I am not going to describe it. :shock:

Sometimes I do this a couple of times when I can so that the tank is clean.

It's a nasty job, but somebody has to do it. :lol:


10-17-2006, 03:08 PM
Hey folks , Do what I do empty the tank at the campground quick flush then fill tank about 1/4 full with water drive home and empty at home always a clean tank that way. :shock: :shock: :shock:


10-17-2006, 03:38 PM
Do you have a dump facility near your house?

10-17-2006, 03:42 PM
Our dump facility is the bathroom here in the house. Or the lawn :D


10-17-2006, 05:11 PM
Bob, When I put the slab in I put E/S/Cable in not water because water is only 20' away. :D :D :D


10-17-2006, 06:09 PM
I have run 50' of underground electric & water from the house to my MH parking space. I don't yet have a means of dumping & with an inquisitive dog running free, won't take a chance of even the grey water above ground, even though I live in the woods.

I originally thought I could dig a small septic with my backhoe; maybe a minimum leech field. But from what I'm reading, that may be more trouble than its worth after the 1st year or so. Also, I've read that you don't want to dump your MH waste into an existing home septic system. So, right now I try to drive home empty, or stop at a local RV repair shop at the last town before I arrive home. He charges $5, but it's better than ending up with a solid cake in my tank after it's all settled.

10-17-2006, 06:29 PM
I would like to add a little trick I have heard about and have used. If you are going to drive with water in the black tank you can add ice and it will help clear out some of the gunck on the side wall. It worked pretty well for me and I think it is worth doing but it is only an idea that I have used. Good luck and Happy Camping.

10-17-2006, 06:34 PM
Bob, We are lucky and have city lines, A few years ago we had to have new lines run from the house to the street I asked the plumber to put a saddle on the line, and now have a dump! 8) 8) 8)