[ImperialCrown]

An intermittent crank sensor would fail regardless of fuel level. I doubt that it would fail only at a 1/4 tank. Next time it doesn't start, check for spark.
The fuel level sensor float may be hanging up inside the tank and there may also be wrong parts (pump or tank) causing problems. I have found some aftermarket (non-OEM) pumps very different than what came out of the car.
Mis-positioned pumps or bent float arms can also rub and stop on the inside wall of the tank. There should be an arrow on the pump and on the tank for lining up (clocking) the proper position.
I doubt that you have a 1/4 tank of water as fuel sloshing around while driving would cause stalls a lot of the time.
The tank should be drained and come down to remove the pump and be examined by a competent service technician.

 

[dana44]

Agree above. If it were water you would be having problems every time you started, gas floats on water, thus the pump and filter sits on the bottom of the tank and it would suck water first. If indeed you are only putting in 11 gallons (roughly) fuel to refill the tank at the quarter tank mark when she dies on you, something is preventing that last five gallons from accessing the fuel pump, whether the pump is too high in the tank or something about the filter itself is preventing fuel from getting low enough to pick the gas up from the lower level.