Interstate coach water pump problems

[solar-guy]

New owner of an 08' Interstate. Water pump works fine when fresh water tank is full but once it gets down to between 3/4 and 1/2 tank it starts acting like the tank is empty or the pump is cavitating. I know there is a screen on either the inlet or outlet of the pump (can't tell from the manual), is there a chance the screen is plugged up?

As a side note the water smelled "funky" when I got the coach so I drained it and refilled it but still smelled. I just finished the recommended bleach treatment from the manual, and now the pump is acting up.

Other ideas?

[Schu]

Do you feel your display panel is reading correctly?

[wayneskid]

Schu is probably onto something; these tank sensors can be flakey!

[Smartstream]

Try running the tank down until the pump starts acting up. Then open the tank drain valve and see how much water runs out. Little or no water means the tank monitor is inaccurate and the pump can't pump what isn't there.

Good luck, Dan

[ROBERTSUNRUS]

Hi, don't trust your tank monitoring system. On a scale from 1 to 10, and 10 being the best, I would rate mine as a 3. My battery meter works, my fresh water works, but not very accurate. My black tank only reads empty, and my gray tank only reads empty or full, but nothing in between. Also if you think you might have a bad tank sensor or two, [I think I do] you will need to hire an Airstream forensic scientist to locate them without removing your tanks. I would like my tank monitoring system to work, but I'm not drilling holes all around my tanks to find the secret locations of these sensors.

[Wsmith]

I would check for empty tank as others have suggested. If you bleach treated the tank you could have released a lot of algae that may have been on the walls of the tank, check the strainer on the inlet line. You should also check for an air leak on the suction side of the pump. It could even be a short suction pipe. flex hoses could collapse also. Mine has a spring inside to prevent that and I still have factory flex hoses on a 1985. I doubt its a flex hose on a new trailer. You can look for suction leak with a little foaming shaving cream on the joints and turn the pump on but you need to verify the pump can run dry if its not picking up some water (most will run dry with no problems) if there is a leak the shaving cream will suck into the suction line.

[solar-guy]

I pulled the intake screen on the water pump and found it plugged with some plastic debris; looked like it might have been plastic shavings from the tanks or the plumbing; anyway once I cleaned that screen the pump works great.

[ROBERTSUNRUS]

Hi, that's great; We always like a happy ending.

[solar-guy]

OK, here's the final happy ending to the story. I talked to Airstream and they had me pull and check the "dip tube" that goes into the tank. Guess what, the dip tube was only 6" long and they sent me a replacement tube that was 12" long. Once I installed that I can actually use all the water in the tank! How in the world they built this thing with a 6" dip tube escapes me BUT the Airstream support has been excellent.

[htsimonton]

how do you access the screen? Thanks

[InterBlog]

This is a common issue for us - we pull that screen and clean it as a preventative measure before each and every overnight if our Interstate has been left sitting even for a short time. Even if it does not completely plug, if there is any kind of a restriction in flow, it greatly worsens the racket from that pump, which was loud to start with. IMO it is undercapacitied for the job it was intended to do, so do not be surprised if you experience a recurrence.

In response to the last or near-to-last poster's question, I would post pics but my rig is not at the house right now.