I never used auto start with my gas powered vacuum pumps but I had an auto off if the tank got full. I ran a wire into the tank at about 3" below the top with an inch or so stripped bare and hooked it to the kill switch on the engine. If it ever got that full the idea was to kill the spark. However, while it got within a few inches of that full, it never had to kill the engine. I only know it would have worked because I added a length of bare wire to hang down enough to short the spark when I hooked it up and the engine quit.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.