Putting the RV onto the larger rear tank (which sometimes will get me all the way home from Lodi Jct.), I drove to Sacramento to visit my sister. When I pulled to a stop near the nursing care facility, there was a strong smell of gasoline. I thought that possibly the spring sunshine had caused fuel from the forward tank to expand and start to go out the overflow, so when I left Sacramento I ran on the front tank for a short distance to burn off some of the possible excess. When I switched back to the rear tank, I was horrified to see it go nearly all the way empty, and before I got to Auburn it ran out completely, less than 70 miles from Lodi Junction.
The obvious conclusion is that there is some sort of leak in the area of the rear fuel tank. Switching to the forward tank, I continued on home to Fernley. There was no leaking-gas smell once the residual odor wore off. Somewhat to my surprise, the tank still registered roughly half full when I got home (I'd rather expected to have to top off in Sparks just to get home). Refueling took only about 8 gallons, which calculates out as roughly 15 miles per gallon. That's absurd. The RV's mileage has been a dependable 8-11 mpg, and going uphill from Sacramento tends toward the lower end, not the upper. Something funny is going on here. And we need to get it fixed as soon as possible because I go back to the Bay Area a week from Sunday. While I could limp along on the smaller tank, it's a bad idea because my range is so limited: about 135 miles or so per tank.
Lisa and I will evaluate our options over the weekend. In any event, I'm home now, and glad to be here.