Yeah it was right around there... maybe could have been as high as 7 gallons, my fuel gauge was dead & the fleabay special I bought worked for about an hour & now just reads slam full... so that was pretty much based on me eyeballing the strainer.
I've only really run it the one outage, which was pretty much exactly 72 hours. I started with the race jug full (which is 6 gallons) and the tank full, I filled the race jug twice right around 24 & 48 hours, and ended up with the race jug almost empty & the day tank close to full when the power came back on.
I don't know what I was pulling though, probably not a ton... which would lead me to my next question, is your vac pump really pulling 17A? (And not just that's the LRA or FLA) Cuz if it actually pulls 2kw, I'd kinda question whether an 831A will start the motor... that's in the realm of what my well pump draws (actually it's about 20% higher) and I had to do some... interesting... things to get the generator to start the well pump. (So, uh, my well pump now has a contactor & voltage-ramping soft-start in the control circuit, instead of just a switch)