I have enjoyed your posts and videos all this time.
We bought our Cougar 277RLS in 2013 and have followed your adventures, and upgrades all along the way.
We travel through Washington and Oregon in the summer/fall months. We have our favorite places, but enjoy when we find new places.
Cheers...

I found that the fuel farm in Auburn Washington offers Regular w/o Ethanol pump gas, and has become my go to for all my small gas engines.
Even though I have become pretty good at rebuilding (or at least cleaning clogged jets), just get rid of the root cause.
I use it all the time, and have not had any carb issues.

One more thing to consider, if you are not using a pressure regulator on you city water hook up, your water pressure could be higher than normal. With a back flow preventer, preventing water to escape the heating/expansion process, it can only escape through the expansion valve.

That video should explain it to all to recreational drivers. It's just not worth it. I bought chains for the truck, but if I think I need a drag chain on the trailer, I'm parking it and plugging in the generator and waiting it out.

I would be curious if the furnace continues to drop out if you bypass the thermostat.

I noticed the meter is for only 50hz applications. Is that what you installed? No negative effects?
I enjoy you posts. OBTW, I have a Cougar 277RLS. Very similar to yours, so your mods are easy to relate too.

I have always wondered, when showering in my Cougar 5th wheel, I have noticed that when I pause the shower with the shower head, when I continue I get a moment of cold water. Maybe this valve is the reason.
During pauses, the water still trickles a small amount, and the water from the supply takes the path of least resistance. This check valve is the resistance, so that is why it it cool water.
Thoughts?

Ezup is still very popular. Our latest popup has uv protection that works well to shelter you from the sun.

That sounds like a good test. If it flows normally, then it is the vent. Likelyhood of being up high where the two tanks tie together, and above.
Remove vent cap, verify no creature or insects have or could get by. I would use a small "snake" to rooter down the pipe from the roof. Not knowing where the tee is in the vent, I wouldn't push it to far.
I'm guessing a insects have made a nest. It will be easy to plow through it.

Maybe if you could include some pictures, we could get a better idea of your configuration and situation. Without some visual, it's like troubleshooting with our eyes closed.

The tailgate on my 2017 superduty opened unexpectedly once while backing my 5th wheel into the carport. It damaged the storage door on the front of the 5th wheel.
At the time I attributed it to me accidentally activating the electronic release with the pod in my pocket, but now I'm wondering if it something tied to this recall?

The Casino in Ocean Shores is one of our favorites. The casino has treated as fairly as well.
My Sister has a place in town as well, so we always have options.
Camping at the casino is dry camping only. Propane fire pits only. We prefer backing up to the ocean side, as our big window is in the back. We use a small generator here.

Enjoy you trip, well be following your post throughout the trip.