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Discussion Starter · #1 ·
Does the Clarity PHEV have an equivalent to the Volt's Fuel Maintenance Mode?

For those of you who aren't familiar with the Volt, it switches to a classic hybrid when the average age of the gas in the tank reaches 360-370 days and will literally burn the tank dry (I know, my Volt ran out of gas about a quarter mile before my preferred gas station) and then keep driving on battery.

My question is has anyone hit something similar in the Clarity PHEV? After 13 months of a full tank of gas I started putting my wife's Clarity into sport mode and did everything I could to burn gas. After two weeks of this I managed to burn half a tank in my daily commute so I refilled the tank at this point. My dealership, where we bought the car knows less about the car than I do, trying to tell me it's like any other hybrid and the gas shouldn't last that long in the tank because the car will use it in normal driving.
 

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Does the Clarity PHEV have an equivalent to the Volt's Fuel Maintenance Mode?

For those of you who aren't familiar with the Volt, it switches to a classic hybrid when the average age of the gas in the tank reaches 360-370 days and will literally burn the tank dry (I know, my Volt ran out of gas about a quarter mile before my preferred gas station) and then keep driving on battery.

My question is has anyone hit something similar in the Clarity PHEV? After 13 months of a full tank of gas I started putting my wife's Clarity into sport mode and did everything I could to burn gas. After two weeks of this I managed to burn half a tank in my daily commute so I refilled the tank at this point. My dealership, where we bought the car knows less about the car than I do, trying to tell me it's like any other hybrid and the gas shouldn't last that long in the tank because the car will use it in normal driving.
Maybe considering your historical usage you should just keep the tank 1/4 full most of the time.
 

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Discussion Starter · #3 ·
Maybe considering your historical usage you should just keep the tank 1/4 full most of the time.
That's actually the goal. I do remember when I suggested this when my wife first got the Clarity I got "stoned" by the full tank brigade because the fuel pump needs to be kept cool. The reality is that if you're not using gas you don't need to worry about the fuel pump temperature. You do want to keep the seals moist however, so you don't want to run dry. (I'm not even sure the Clarity's drive train will operate without gas in the tank.)
 

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That's actually the goal. I do remember when I suggested this when my wife first got the Clarity I got "stoned" by the full tank brigade because the fuel pump needs to be kept cool. The reality is that if you're not using gas you don't need to worry about the fuel pump temperature. You do want to keep the seals moist however, so you don't want to run dry. (I'm not even sure the Clarity's drive train will operate without gas in the tank.)
My wife is a “fill the tank at any possible opportunity” type of person. She’s starting to get the idea that the only time we really need gas is when we make an out-of-town trip. And as infrequently as we really need gas it doesn’t make that much sense to carry around a full tank for hundreds of miles (even though 7 gallons only weighs about 45 pounds).
 

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My wife is a “fill the tank at any possible opportunity” type of person. She’s starting to get the idea that the only time we really need gas is when we make an out-of-town trip. And as infrequently as we really need gas it doesn’t make that much sense to carry around a full tank for hundreds of miles (even though 7 gallons only weighs about 45 pounds).
[/QUOT.

Seems to me that the oweners manual should provide info on all these questions concerning ICE maintenance during various use conditions. The owners manual is basically worthless for DIY type folks like me!😣
 

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I'm gonna top mine up before winter takes, usual precaution for an ICE tank to keep condensation and gas line icing in check. I guess this applies to my Clarity PHEV
 

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I'm gonna top mine up before winter takes, usual precaution for an ICE tank to keep condensation and gas line icing in check. I guess this applies to my Clarity PHEV
The Clarity PHEV has a sealed fuel system. Unless the fuel you buy contains water, condensation shouldn't be a problem. Gasoline freezes at roughly -40F (-40C) and ethanol at roughly -175F (-114C). I don't think I'd be driving anything at -40F.

 

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The Clarity PHEV has a sealed fuel system. Unless the fuel you buy contains water, condensation shouldn't be a problem. Gasoline freezes at roughly -40F (-40C) and ethanol at roughly -175F (-114C). I don't think I'd be driving anything at -40F.

I would be very suprised if it was a sealed system, you would be creating a vaccum when you use up gas in winter and a pressurized tank in summer that could make filling up very interesting. Gas tanks need to be at or near atmospheric pressure IMHO, so air sucked in or pushed out depending on the temperature and gas consumption and that is how humidity can come in. I've always kept my tanks full during the transition period in fall and spring and never had a line freeze.
 

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Discussion Starter · #10 ·
I would be very suprised if it was a sealed system, you would be creating a vaccum when you use up gas in winter and a pressurized tank in summer that could make filling up very interesting. Gas tanks need to be at or near atmospheric pressure IMHO, so air sucked in or pushed out depending on the temperature and gas consumption and that is how humidity can come in. I've always kept my tanks full during the transition period in fall and spring and never had a line freeze.
Honda and Chevy (Volt) both use sealed fuel systems that pump conditioned (dry) air in as needed to maintain a positive vapor pressure. This prevents leaks from sucking in moisture.
 

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Thanks, I learned something. I guess they have an activated carbon trap on the fuel vapor recirculation. This may work for a while until it gets saturated. I wonder if they have a way to recondition it or maybe I'm way off and it's another method all together. Again I dont know just curious.
 

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Thanks, I learned something. I guess they have an activated carbon trap on the fuel vapor recirculation. This may work for a while until it gets saturated. I wonder if they have a way to recondition it or maybe I'm way off and it's another method all together. Again I dont know just curious.
Small airplanes have a device called a gascolator which is a bowl that sits below the gas tank. Water is heavier than gas so it makes its way down and settles in the bowl. Before you fly you just obtain a tester of fuel from a valve on the bottom of the gascolator. If there’s no water in it, you’re good to go. If you find water just keep drawing until there is no water in the sample.
 

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Discussion Starter · #13 ·
Thanks, I learned something. I guess they have an activated carbon trap on the fuel vapor recirculation. This may work for a while until it gets saturated. I wonder if they have a way to recondition it or maybe I'm way off and it's another method all together. Again I dont know just curious.
Fuel vapors aren't the problem. They'll evaporate back out of the filters. The issue is fuel contaminates getting into the evaporative recirculation filter. Contaminates are the reason you don't want to religiously fill your tank to the top of the fill pipe as they remain in the filter even after the gasoline evaporates back out.
 

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Honda and Chevy (Volt) both use sealed fuel systems that pump conditioned (dry) air in as needed to maintain a positive vapor pressure. This prevents leaks from sucking in moisture.
Yup, but with a caveat. 2011 Volt fuel systems were not sealed well enough to pass CA requirements for ZEV carpool stickers. GM fixed the issue in subsequent model years.
 

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Small airplanes have a device called a gascolator which is a bowl that sits below the gas tank. Water is heavier than gas so it makes its way down and settles in the bowl. Before you fly you just obtain a tester of fuel from a valve on the bottom of the gascolator. If there’s no water in it, you’re good to go. If you find water just keep drawing until there is no water in the sample.
Tractors and a lot of trucks have a similar device which is operating on the density difference between diesel and water, it would also work between gasoline and water. The bowl can be placed anywhere since it is simply the density difference which sends the water at the bottom of the bowl. There is actually a little valve at the bottom of the bowl, opening the valve will throw out the water content and a bit of fuel. If there is water, it is actually easy to visualise it. I have never seen such a device in a car, I suppose they could but to keep costs down, manufacturer do not included it.
 

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Discussion Starter · #16 ·
I would be very suprised if it was a sealed system, you would be creating a vaccum when you use up gas in winter and a pressurized tank in summer that could make filling up very interesting. Gas tanks need to be at or near atmospheric pressure IMHO, so air sucked in or pushed out depending on the temperature and gas consumption and that is how humidity can come in. I've always kept my tanks full during the transition period in fall and spring and never had a line freeze.
It's a sealed system. All passenger cars have sealed system gas tanks and will actually throw a CEL if there's a pressure drop while driving. The car operated powered vents to ensure the vapor pressure is consistent during driving. The Clarity (and Volt) have even tighter seals because they don't go through gas quickly. These tighter seals keep the pressure consistent even when the car is off.
 
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