Underground tanks don't change in temperature much if at all. The sun only warms the top 6" or so. Down where the tanks are it should stay 55-60 degrees pretty much all the time. If you touch the nozzle and it feels hot it's not because the underground tank is hot. If the gas is heated up at all it's because of the pump. But most likely it feels hot because of the ambient air temperature, especially if the pump is on the end where the sun can creep onto it at certain times of day. All the ones I remember feeling were actually cold.
Ummm.... Isn't the fuel pick-up near the bottom of the tank (cars or the underground storage) anyway?
The concern about filling the underground tank with a fresh load and 'stirring up' sediment in it doesn't make sense if the bottom of the tank is from where all the fuel for all those prior cars has come. Any sediment that settled at or near the bottom would be long gone.
Ditto for the car's fuel tank. The fuel and any heavier than fuel debris at the bottom of the tank is the first to be drawn to or into the fuel lines. The action of driving itself continues to mix the contents of the fuel tank continually keeping the debris moving and available for pick up.
Chain saws, string trimmers, other multi position motors that use a floating pick-up to prevent fuel starvation when operated inverted are obviously not part of this group.
A 12 gallon tank filled when the level drops to 2 will have 6 stops for fuel, while filling when the level drops down to 6 remaining will require 10 stops for the same 60 gallons of fuel consumption. The extra time to put in the four added gallons of fuel those six episodes is small in comparison to the time to pull in, uncap the tank, pay, start and drive off the four additional stops.
The fuel filters in my diesels do have a water separator chamber at their base that is a scheduled maintenance item. Each 15k miles the drain is to be opened for the content to be drained (and examined). I haven't ever seen any, fwiw.
oh, whoops I glazed over where it said stir up water in the UST. Was talking about sediment in the beginning and I guess I assumed you were still talking about it at the end of the paragraph. That was after a 16 hour work day, I was kinda tired.
The fuel pickup is near the bottom, but not at the bottom so you don't directly suck up water and sediments. Sure, fuel filters filter sediments out, but if you can avoid the sediments and water by not fueling if you see a tanker truck in the lot, why not? At the very least, you are paying for water and sediments at over $4.00/gallon and you either filter them out, or they make your car run like crap.
In the grand scheme of things say you get a 15 gallon tank of fuel while the tanker truck is there. Let's say that 1/2 of 1% of that 15 gallons is water. That's 0.075 gallons of water. Multiply this by $4.00/gallon and you've paid $0.30 for water you can't burn, and you can't drink. When I was in high school I used to work for an air conditioning company. The owner of the company was from Kentucky and had a saying... Never spend your money on anything you can't eat, burn, or screw.
I seldom go below a half tank anymore. I have had to drop the fuel tank on my '88 Escort a couple of times to replace the fuel pump and the actual pump is near the halfway point. As others have pointed out the fuel in the tank is also used to keep the fuel pump cool. Each time I have had a fuel pump go out the tank was at or below 1/4. The extra stops are well worth the trouble compared to having to drop the fuel tank and replace the fuel pump, although lots of cars now have access to the fuel pump by simply removing the rear seat.
I would think the 10% ethanol here would emulsify any water in the tanks, just like the additives you used to use for the same purpose.
I was thinking that also, but it was mentioned in another thread that water will come out of solution at 97% or less ethanol when the alcohol is mixed with gas. Pure ethanol is also hygroscopic. It will suck moisture out the air it is in contact with until it reaches 95.5%. So pure ethanol, if it chance to absorb water, will release some of that water when mixed with gasoline.
Perhaps it can still emulsify the water, but that isn't as good dissolving the water in terms of getting it out of the tank.