My take on this, and I freely admit my take is nothing but a guess. To me it sounds like you were down to less than 10 gallons in the truck when you parked it. It saying you had 98 miles DTE on parking, what is your average MPG? For me 98 miles DTE would be in on the order of 7 or 8 gallons left under average conditions, maybe as low as 6 gallons left, generally not as much as 10 left. And you parked it on a hill facing down.
Both of the Raptor tanks, the 26 G and the 36 G, are long, narrow, tanks. The 36 gallon tank is over 6 feet long and only about 20 inches wide. The fuel pickups for both sized gas tanks are behind the center point, i.e. closer to the back than the front. Both tanks have a shallow well or depression in the area under and around the fuel pump and pickup. This well should keep fuel centered around the pump with the vehicle in motion and sloshing, even with a nose up or nose down attitude.
None of the below images are mine, I grabbed them off the web. I did add the lines and the angles.
These are the two tanks, the 36 gallon tank is the one in the back. The left side of the image is vehicle forward, the right side is vehicle back. The white'ish round section on top of each tank is the top of the fuel pump / gauge / pickup.
View attachment 303149
Below is the tank with a notional fuel level in it, call it a bit less than a quarter tank. You can see that the fuel pump is the lowest part in the system, with the bottom everywhere else sloping towards it.
View attachment 303150
Now I have rotated the fuel tanks 6 degrees vehicle nose down, leaving the red lines alone. The fuel pump well is no longer the lowest part of the system. The "nose" of the tank is significantly lower than the fuel pump, and the fuel has all shifted towards the front, away from the pump
View attachment 303151
To me it looks like the system is biased towards the rear. I mean if the fuel shifts rear wards the system continues to pick the fuel up well and the shape of the tanks minimize bunching to the rear. This makes sense to me. Under acceleration or going up a hill is the worst possible time for fuel starvation so you design to reduce that risk.
Ideally, of course, you would cover all bases and have no "bad" conditions, but real world engineering is managing those risk with realistic solutions that fit the mechanical requirements of the system. You fit it where you can and make it work the best you can in that location.
I see the same issue, but reversed, filling the tank as draining it. I have noted that I can put a little more fuel in the tank if the vehicle is slightly nose down than I can if the vehicle is slightly nose up.
T!
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