There is a condition that shows a full fuel tank but the engine sputters and eventually stops … you’re out of fuel — sort of.
If either the left or right fuel cock is closed, fuel will not balance out between the two lobes of the tank. With the fuel pump on the left and the fuel level sensor on the right you get a full indicator on the dash (because the right side is full) and a pump sucking the left side dry.
Both fuel cocks need to be closed to remove the tank. If your shop or you forget to reopen them expect to run out of gas early. (Mine came from the dealership with the right side closed.)
Luckily each fuel cock can be accessed and opened or closed without tools or removing any parts — the left side more easily than the right.
On the left, duck your head under the fuel tank and you’ll see the knurled knob right there. Turn it counterclockwise to open.
On the right you’ll have to jam your had under the tank lobe and feel around.
The blurry clip on the right side of the above photo is the electrical connection to the fuel level sensor and is easily visible. The fuel cock is further to the front and more difficult to see.
If you can’t reach the knob, find someone with smaller hands or remove the right side tank guard. Again turn the knob counterclockwise to open.
Here are a couple screengrabs from the R repair manual for further reference. The first picture is the right side, second is left, and third is right again.