Per their site:
"40 Gal Fuel Station Road Side"
I'll be interested to see what others chime in with. I ran my generator for 2 hour so far, with only the fuel that someone put in there when I picked it up. I plan to fill it up later on and I'll see too.
I had a 36 gal tank on my F-150 but I could run it 10 miles beyond the "0 miles left" in the display and only get 32.5 gallons in it. Ford told me (I called customer service and opened a ticket for their engineers) it was due to the baffling inside to limit sloshing, etc. so you never get the full size.
That pissed me off. It should have been a 33gallon tank then.
TH : 2016 Stealth WA2916
TV : 2012 Ford F-250 PSD