best fuel level to maintain

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On 08/05/2016 2:55 PM, Jake wrote:

Well, I'm not positive they're really experts; the following white paper says they're using a factor of 10X too low for the solubility/phase separation point--0.05% vis a vis 0.5%. I'm inclined to believe the latter over the former as being "more expert".
Even if the former were correct, it's still only 2.5% of the saturation volume in 100% RH air if were to condense it all. I'd be willing to listen if somebody could recompute independently and show gross error in the above estimate.
If it were such a problem as the above reference claims, it'd be happening all over the US in such high numbers there'd be no way the issue couldn't be addressed. I think they're simply over-reacting to the possibilities of clean fuel contamination. _Getting_ contaminated fuel from a service station, otoh, does happen fairly regularly owing to water entrance into USTs by various mechanisms or other ways of introducing water in bulk into supplies. But starting with clean fuel in a vehicle tank from condensation? Nah, ain't agonna' happen...
<http://www.veeder.com/gold/download.cfm?doc_idi35 (PDF DOC link to a readable white paper on the subject by vendor of prevention/mitigation systems for bulk suppliers)
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On 08/05/2016 2:55 PM, Jake wrote:

Well, as noted before, I wasn't convinced by their analysis having done the calculation so I kept looking and found another white paper; this one by EPA
It draws the same conclusions I did--
"Phase separation, however, generally only occurs when liquid water (as opposed to water vapor) is introduced to the fuel system. If tank vents are left open, either in the engine being operated, or at a fuel distribution station, water can enter the fuel system in the form of rain (or spillage, etc.) or through the air in the form of moisture. Also, since conventional gasoline absorbs very little water, there is often a layer of water present at the bottom of a filling station tank normally used to store conventional gasoline (water is more dense than gasoline, and will therefore sink to the bottom). Before an oxygenated gasoline is added to such a storage tank for the first time (particularly ethanol-blended fuels), this water must be purged from the tank to prevent the water from removing any ethanol from the fuel.
Since the solubility of water in both gasoline and air decreases with a decrease in temperature, water can enter a fuel system through condensation when the atmospheric temperature changes. For example, assume a tank containing conventional gasoline contains only one gallon of fuel. Assume also that it is closed while the outside temperature is 100 degrees F with a relative humidity of 100 percent. If this tank is left sealed and the temperature drops to 40 degrees F, water will likely condense on the inside of the tank, and dissolve in the fuel. In order for enough water to condense from the air to cause gasoline-water phase separation, however, there must be approximately 200 gallons of air per gallon of fuel over this temperature drop (100 to 40 degrees). Since oxygenated fuels can hold even more water than conventional gasoline, it is even more unlikely that enough water will condense from the air to cause gasoline-water phase separation."
The 200:1 ratio almost precisely duplicates my earlier estimate...I just quoted it over a differing volume and in alternate units. I did note that while I hadn't computed it, the 3.8 tsp measurement your reference used is referred to in this document but they mis-computed/mis-typed the percentage in the 0.05%; it is 0.5%.
So, anyway, the problem of phase separation in E10 of initially clean fuel in a clean tank occurring owing to moisture condensation from the air introduced alone is simply a non-issue.
<http://www.epa.gov/sites/production/files/2015-09/documents/waterphs.pdf>
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On Thursday, August 4, 2016 at 3:32:40 PM UTC-4, Frank Thompson wrote:

just have the fuel pump in your gas tank die because you have run it dry too often, cost 600 bucks and up/
and if your intelligent you will keep tank mostly full
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bob haller wrote:

I replaced mine myself on my 1969 Buick pretty cheap. Have they changed that much in 47 years?

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On Saturday, August 6, 2016 at 9:27:44 PM UTC-4, Bill wrote:

minimum price for a aftermarket in tank pump assembly 300 to 400 bucks.
for a brand new OEM pump at least 600 bucks and often more. pumps include fuel gauge and fuel filter. the gasoline in the tank cools the pump. run the tank low or out, espically in hot weather, fries the pump.......
my 1969 impala had a fuel pump fail, a easy replacement bolted to the engine.. i think it cost 40 bucks
far cheaper to always keep the tank at least half full.
but its your money and your back, feel free to replace them as often as you want..........
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wrote:

I've replaced a few, one last year. That one was an Bosch for $142.50. They have never cost me much more than that. You might pay $600 for shop to drop the tank and replace.
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On Thu, 4 Aug 2016 12:32:35 -0700 (PDT), Frank Thompson

as critical on a properly functioning late model, but still adviseable
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