Author Topic: That pesky low fuel warning and the disappearance of the range function.  (Read 38043 times)

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Offline ST eater

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On my 04 ST, the fuel count down would go to 20mi left when on reserve. That's one thing I liked about that fuel gauge, no taking over the whole screen and it had a count down. But the first time it flatlined with 20mi to go, I thought I was in deep do do! :-[ these bikes would not be fun to push. I want one of these, I really dislike the current set up.
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Offline PaleRider

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On my 04 ST, the fuel count down would go to 20mi left when on reserve. That's one thing I liked about that fuel gauge, no taking over the whole screen and it had a count down. But the first time it flatlined with 20mi to go, I thought I was in deep do do! :-[ these bikes would not be fun to push. I want one of these, I really dislike the current set up.

Yes, automatically, as soon as it hit reserve it started counting backward  based on the your current MPG. It was pretty darn accurate. Don't mean to say was as I can see my 04 ST1300 from where I am sitting in my shop.
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Offline Cap'n Bob

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On my 04 ST, the fuel count down would go to 20mi left when on reserve. That's one thing I liked about that fuel gauge, no taking over the whole screen and it had a count down. But the first time it flatlined with 20mi to go, I thought I was in deep do do! :-[ these bikes would not be fun to push. I want one of these, I really dislike the current set up.


   I kind of like how the FJR does it. When it goes on low fuel warning, you get a small warning on the screen to go along with the other existing information. The only change to said information is that the odometer/trip gage then starts counting from zero. It's a how far you have traveled since you went on low warning  deal rather than how far you might be able to go. (just my preference) I like that a little better than how far I might be able to go. although neither hurts to have.
     Although the truth be told, I get very anxious about fuel levels. So I try to find fuel before I get to the low fuel warnings. But if it does come on, I find a station as soon a possible. I have seen reserves that didn't pick up anywhere near the amount of fuel they are suppose to have. (The Kawasaki Mean Streak is notorious for this) So I try not to chance fate (or running out) Of course I have the luxury of living on the east coast where fuel stations tend to be in fairly close proximity compared to other parts of the country, or world for that matter.

Offline BDF

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Yep, there are different ways to use warnings / indicators and some are better than others. That said, the whole thing is really everyone's opinion anyway; look at the folks who want taller / shorter handlebars, taller / shorter windshields, etc. etc. So in the end the mfg. has to pick one and forge ahead.

Never had an FJR so cannot comment on the way they display anything but obviously I think the C-14 display can be improved.

Good point about where we live and ride. Here in southern New England fuel isn't much of a problem nor is the time of day you want it. Not so much in Wyoming though where there are long stretches of highway either without many fuel stations or stretches where the fuel stations shut down at night.

I guess my biggest personal complaint with the C-14 is the range display; it shuts down at the only time I care about what it might be telling me- when I am low on fuel. Everything else I could live with and while the warning display is annoying, it  can be shut down given enough tries at the magic button sequence. The range disappearing just cannot be dealt with, at least with anything Kawasaki provides.

Low fuel on the C-14 seems to be notoriously accurate though and it is absolutely repeatable. Same thing with the volume of the fuel tank- Kawasaki claims 5.8 gallons but every one I have seen will hold over 6 gallons. Not a big deal maybe but much, much better than the occasional one holding 5.5 gallons (surprise!).

Brian


   I kind of like how the FJR does it. When it goes on low fuel warning, you get a small warning on the screen to go along with the other existing information. The only change to said information is that the odometer/trip gage then starts counting from zero. It's a how far you have traveled since you went on low warning  deal rather than how far you might be able to go. (just my preference) I like that a little better than how far I might be able to go. although neither hurts to have.
     Although the truth be told, I get very anxious about fuel levels. So I try to find fuel before I get to the low fuel warnings. But if it does come on, I find a station as soon a possible. I have seen reserves that didn't pick up anywhere near the amount of fuel they are suppose to have. (The Kawasaki Mean Streak is notorious for this) So I try not to chance fate (or running out) Of course I have the luxury of living on the east coast where fuel stations tend to be in fairly close proximity compared to other parts of the country, or world for that matter.
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Offline Jeff Kerkow

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Received mine on Friday, have not had chance to install yet but the instructions look good and the process looks very simple.

Great idea and great service

Thanks
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Offline mattchewn

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Hey,
I just had a great idea! How about you don't run the tank to empty all the time and then you don't get that pesky warning thingy? Having been a mechanic/tech for many years I am not a fan of running any fuel tanks down towards the bottom if it is avoidable. I will explain why; On FI motors in bikes, cars, etc. the fuel pump is cooled off by the fuel in the tank and the lower the fuel level the less the cooling ability. Notice your tank starts getting warmer as you run the level lower.  Also, the lower the level of fuel the harder the pump has to work to maintain fuel pressure at the correct level. In cages, and most probably in bikes as well, running the fuel level low allows the fuel to slosh in the tank excessively and that stirs up any trash that may have found its' way into your tank, (trust me it is there), and it the gets picked up by your expensive fuel pump. In my truck I rarely run below 1/4 tank.
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Offline lather

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I think I would like this mod for trips but not for commuting. Is it fairly easy to put on and take off?
If so count me in on the next batch.

Yep, there are different ways to use warnings / indicators and some are better than others. That said, the whole thing is really everyone's opinion anyway; look at the folks who want taller / shorter handlebars, taller / shorter windshields, etc. etc. So in the end the mfg. has to pick one and forge ahead.

Never had an FJR so cannot comment on the way they display anything but obviously I think the C-14 display can be improved.

Good point about where we live and ride. Here in southern New England fuel isn't much of a problem nor is the time of day you want it. Not so much in Wyoming though where there are long stretches of highway either without many fuel stations or stretches where the fuel stations shut down at night.

I guess my biggest personal complaint with the C-14 is the range display; it shuts down at the only time I care about what it might be telling me- when I am low on fuel. Everything else I could live with and while the warning display is annoying, it  can be shut down given enough tries at the magic button sequence. The range disappearing just cannot be dealt with, at least with anything Kawasaki provides.

Low fuel on the C-14 seems to be notoriously accurate though and it is absolutely repeatable. Same thing with the volume of the fuel tank- Kawasaki claims 5.8 gallons but every one I have seen will hold over 6 gallons. Not a big deal maybe but much, much better than the occasional one holding 5.5 gallons (surprise!).

Brian


   I kind of like how the FJR does it. When it goes on low fuel warning, you get a small warning on the screen to go along with the other existing information. The only change to said information is that the odometer/trip gage then starts counting from zero. It's a how far you have traveled since you went on low warning  deal rather than how far you might be able to go. (just my preference) I like that a little better than how far I might be able to go. although neither hurts to have.
     Although the truth be told, I get very anxious about fuel levels. So I try to find fuel before I get to the low fuel warnings. But if it does come on, I find a station as soon a possible. I have seen reserves that didn't pick up anywhere near the amount of fuel they are suppose to have. (The Kawasaki Mean Streak is notorious for this) So I try not to chance fate (or running out) Of course I have the luxury of living on the east coast where fuel stations tend to be in fairly close proximity compared to other parts of the country, or world for that matter.

Offline BDF

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Well it sounds like you have some solid opinions that you use to operate your equipment. Good for you, and the best of luck with your technique.

I would mention that your physics is a bit off though. The whole 'fuel tank gets warmer' when the fuel level is low is not correct; if the fuel is what is cooling the pump, where does the heat in the fuel itself go? Yep, it passes through the fuel into the walls of the tank and out into the universe (thereby keeping the entropy in the universe constantly increasing). So no matter what the fuel level, the fuel pump will always generate the same amount of heat and the fuel level cannot increase or decrease that heat, only transfer it.

As far as stirring up crud in the tank, the fuel pump is located in the lowest part of a sloped fuel tank on the C-14; all the crud had already settled around the pump. As fuel pumps draw fuel in from the bottom, the fuel system was already exposed to everything in there. Your pickup truck is not a valid comparison because the tank is much wider / longer and has multiple flat planes along the bottom.

I have never been certified by the ASE and of course, will not discuss my bonifides so as always, I advise everyone reading this to weigh the information given, judge the writers and come to your own conclusions.

Brian

Hey,
I just had a great idea! How about you don't run the tank to empty all the time and then you don't get that pesky warning thingy? Having been a mechanic/tech for many years I am not a fan of running any fuel tanks down towards the bottom if it is avoidable. I will explain why; On FI motors in bikes, cars, etc. the fuel pump is cooled off by the fuel in the tank and the lower the fuel level the less the cooling ability. Notice your tank starts getting warmer as you run the level lower.  Also, the lower the level of fuel the harder the pump has to work to maintain fuel pressure at the correct level. In cages, and most probably in bikes as well, running the fuel level low allows the fuel to slosh in the tank excessively and that stirs up any trash that may have found its' way into your tank, (trust me it is there), and it the gets picked up by your expensive fuel pump. In my truck I rarely run below 1/4 tank.
JMO, and what do I know anyway?
ASE Certified Master Auto Tech 1995-2005.
KiPass keeping you up at night? Has the low fuel warning burned your retinas? Find peace, harmony and the answer to these problems. www.incontrolne.com

Offline BDF

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Pretty easy- other than taking off the saddle, easier than changing a headlight IMO. It is nothing more than what amounts to an extension cord type of harness that plugs into a harness on the bike. Exactly like the KiPass activation switch bypass but this harness on the bike is easier to get to and requires no tools or removal of bike parts.

Brian

I think I would like this mod for trips but not for commuting. Is it fairly easy to put on and take off?
If so count me in on the next batch.

KiPass keeping you up at night? Has the low fuel warning burned your retinas? Find peace, harmony and the answer to these problems. www.incontrolne.com

Offline BDF

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Thanks for the kind words.

Well, that's it folks- these things are loose in the wild now and there won't be any stopping the process. Yep, from now on each and every single time you see a C-14 anywhere in the world, you will have to wonder.....'Does THAT bike have one of those neat low fuel warning eliminators?'

 :rotflmao:

Please do let us know how the install goes and how you like it.

Brian

Received mine on Friday, have not had chance to install yet but the instructions look good and the process looks very simple.

Great idea and great service

Thanks
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Offline lather

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Pretty easy- other than taking off the saddle, easier than changing a headlight IMO. It is nothing more than what amounts to an extension cord type of harness that plugs into a harness on the bike. Exactly like the KiPass activation switch bypass but this harness on the bike is easier to get to and requires no tools or removal of bike parts.

Brian

I think I would like this mod for trips but not for commuting. Is it fairly easy to put on and take off?
If so count me in on the next batch.

Sounds great. I will just plug it in whenever I head out of state but for commuting I will still rely on that helpful pesky red light to remind me to get gas.

Offline Roger M.

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Any idea when more will be available??  >:D


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Offline BDF

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Yeah, yesterday and those are all gone too, or at least the people on the list have been made aware of how to proceed with the purchase. Now I am out of some key components and cannot have any more until the end of this week at the earliest.

It is tough to predict the sales of things like this- how many for an initial order.... 20, 50, 200? The components are expensive and I do not want to stock them and manufacturer, say, 200 circuits only to have 15 sell. On the other hand, if I put together 50 of them and get 75 orders in 24 hours, I cannot get the components and quickly enough that I feel comfortable selling the product in advance; several of the parts come from Japan and even with air shipping it takes a bit of time to clear US customs. The next batch of long- lead items has been ordered, and I will order more of everything procured in the US tomorrow (holiday today) and once everything arrives, I promise to whip those elves and not allow them food or bathroom breaks until every last 'I want one' is satisfied. Sure it's hard on the elves but we are motorcyclists and should not have to wait one extra second for our farkles :-)

Seriously, I am on it and will provide product as soon as possible. Thanks for the interest.

Have also ordered Japanese components for the next trinket which I think some folks are going to like. We will see. There isn't an orifice on a C-14 that I have not thought of plugging something into.... wait, I mean adding electronical (one of my very favorite words)  farkles of course.

Brian

Any idea when more will be available??  >:D
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Offline Gypsy JR

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Still want one, and sent you a PM too.
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Offline mattchewn

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Quote:
I would mention that your physics is a bit off though. The whole 'fuel tank gets warmer' when the fuel level is low is not correct; if the fuel is what is cooling the pump, where does the heat in the fuel itself go? Yep, it passes through the fuel into the walls of the tank and out into the universe (thereby keeping the entropy in the universe constantly increasing). So no matter what the fuel level, the fuel pump will always generate the same amount of heat and the fuel level cannot increase or decrease that heat, only transfer it.


    Actually the physics are flawless. More fuel in the tank means more surface area to distribute heat= faster transfer and lower total heat buildup. As the fuel level decreases the ability to dissipate heat is subsequently diminished. Thereby increasing the average temperature of the fuel.  Think of trying to cool your favorite beverage  standing up in a cooler with one inch of ice in the bottom. In your math it will cool the entire beverage just as fast and as cold as if the cooler was full to the top with ice and therefore completely covering the outer surface of said beverage. You might want to reexamine your thermal dynamics principals.
Matt
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Offline Jeff Kerkow

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Farkle installed. It took less then ten seconds. I have already had my tank off so the plug in was readily accessible. Now i just have to run the tank empty to test.

Matt, as far as putting fuel in at 1/4 or more. I came off a C10 so this tank is already to small. To cut it back by another 25% is totally unacceptable for the way I ride.
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Offline JimA

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On my 04 ST, the fuel count down would go to 20mi left when on reserve. That's one thing I liked about that fuel gauge, no taking over the whole screen and it had a count down. But the first time it flatlined with 20mi to go, I thought I was in deep do do! :-[ these bikes would not be fun to push. I want one of these, I really dislike the current set up.
The current generation of Yamaha FJR's activate a third trip meter when the fuel gets low. You always have two trip meters, like the Connie, but then you get a "Reserve" trip that counts up from zero to tell you how long you've been on "reserve." They leave it to you to figure out how far you can go on 1.5 gallons. I liked that set-up.
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Offline BDF

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Er..... well, let me take one more stab at this for the innocent that might be following along- and my explanation does not require or depend on beer or the bottles that may contain it.

If you have a given device (the fuel pump) that puts out a fixed amount of heat (it does as the energy going into it is constant), the surrounding medium MUST dissipate that amount of heat. All heat generated by the fuel pump only has two outlets; the fuel going out to the engine, which we can treat as a constant but in any event the amount of cooling done through that medium is small, and the shell of the fuel tank itself because it houses the fuel pump. The fuel in-between the heat generating unit (the pump) and the elimination of that heat from our model (the motorcycle itself, specifically the outer wall of the fuel tank) does not impact the amount of heat transferred.

By the way, it is not my physics or my math; others figured this out long ago, wrote it down and it has been passed along every since. Bernoulli's principle is not intuitive but it does seem to be correct.

At any rate, whatever works for you. Certainly there is nothing wrong with keeping a vehicle's fuel tank above a certain minimum, even if that minimum is arbitrary or different from other's minimum levels.

Have a nice day (seriously, not sarcastically).

Brian

Quote:
I would mention that your physics is a bit off though. The whole 'fuel tank gets warmer' when the fuel level is low is not correct; if the fuel is what is cooling the pump, where does the heat in the fuel itself go? Yep, it passes through the fuel into the walls of the tank and out into the universe (thereby keeping the entropy in the universe constantly increasing). So no matter what the fuel level, the fuel pump will always generate the same amount of heat and the fuel level cannot increase or decrease that heat, only transfer it.


    Actually the physics are flawless. More fuel in the tank means more surface area to distribute heat= faster transfer and lower total heat buildup. As the fuel level decreases the ability to dissipate heat is subsequently diminished. Thereby increasing the average temperature of the fuel.  Think of trying to cool your favorite beverage  standing up in a cooler with one inch of ice in the bottom. In your math it will cool the entire beverage just as fast and as cold as if the cooler was full to the top with ice and therefore completely covering the outer surface of said beverage. You might want to reexamine your thermal dynamics principals.
Matt
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Offline BDF

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Glad the install went well for you.

I would just like to point out that there is no need nor any advantage whatsoever in removing the fuel tank to install this device. The wiring is readily accessible with the fuel tank in place and everything else in place on the motorcycle. I just don't want anyone to get the idea that removing the fuel tank is needed or even helps with the installation.

Brian

Farkle installed. It took less then ten seconds. I have already had my tank off so the plug in was readily accessible. Now i just have to run the tank empty to test.

Matt, as far as putting fuel in at 1/4 or more. I came off a C10 so this tank is already to small. To cut it back by another 25% is totally unacceptable for the way I ride.
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Offline mattchewn

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LSGiant,
The 1/4 tank was in regards to my truck. Big tank, (38 gal) not far enough distances.  In my bike I run for 180-200 miles= not flashing yet, and then get fuel. Im not interested in finding out the maximum amount of fuel that my tank will hold, i.e. ran out. I know there are times when fuel is not readily available, or it aint convenient etc. I just want to keep things running as long as I can with a minimum of unscheduled maintenance. Please feel free to drive, fuel, (or not fuel) your bike, car, truck, lawnmowers, as u see fit!! Happy riding!
Matt
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Offline BDF

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Yep, a different way to do things.

The way Kawasaki implements the range function, at least after it is allowed to work properly with the addition of a <ahem> particular gadget, is more reflective of how the vehicle is actually used. The odometer function tells the rider how many miles have been traveled since hitting the low fuel level that is not combined in any way with the currant rate of fuel usage. The range function on a C-14 does calculate the range based on the remaining fuel being consumed at the current rate so the rider can regulate the rate of fuel consumption by backing off the bike's speed for example, and have that change be reflected in real- time on the LCD range function. The FJR will display the miles traveled but the rider has no way to know the fuel consumption rate from the time the low fuel warning was reached; sure you can tell you've gone 25 miles for example but how many miles do you have on reserve at the current temperature, speed, altitude, and load on the engine?

Of course each of us will like or dislike different methods as we should I think. Besides, I cannot add a [low fuel miles traveled] function to the Kawasaki, only adjust what is already there.

Brian

The current generation of Yamaha FJR's activate a third trip meter when the fuel gets low. You always have two trip meters, like the Connie, but then you get a "Reserve" trip that counts up from zero to tell you how long you've been on "reserve." They leave it to you to figure out how far you can go on 1.5 gallons. I liked that set-up.
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Offline Pistole

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- re the heat issue :

- in a motorcycle application , the heat generated by the fuel pump in the tank is perhaps irrelevant when compared to the heat generated by that big engine underneath the tank cooking the tank (and whatever fuel there is in it).
.

Offline Don Carruthers

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Well it sounds like you have some solid opinions that you use to operate your equipment. Good for you, and the best of luck with your technique.

I would mention that your physics is a bit off though. The whole 'fuel tank gets warmer' when the fuel level is low is not correct; if the fuel is what is cooling the pump, where does the heat in the fuel itself go? Yep, it passes through the fuel into the walls of the tank and out into the universe (thereby keeping the entropy in the universe constantly increasing). So no matter what the fuel level, the fuel pump will always generate the same amount of heat and the fuel level cannot increase or decrease that heat, only transfer it.

As far as stirring up crud in the tank, the fuel pump is located in the lowest part of a sloped fuel tank on the C-14; all the crud had already settled around the pump. As fuel pumps draw fuel in from the bottom, the fuel system was already exposed to everything in there. Your pickup truck is not a valid comparison because the tank is much wider / longer and has multiple flat planes along the bottom.

I have never been certified by the ASE and of course, will not discuss my bonifides so as always, I advise everyone reading this to weigh the information given, judge the writers and come to your own conclusions.

Brian

Hey,
I just had a great idea! How about you don't run the tank to empty all the time and then you don't get that pesky warning thingy? Having been a mechanic/tech for many years I am not a fan of running any fuel tanks down towards the bottom if it is avoidable. I will explain why; On FI motors in bikes, cars, etc. the fuel pump is cooled off by the fuel in the tank and the lower the fuel level the less the cooling ability. Notice your tank starts getting warmer as you run the level lower.  Also, the lower the level of fuel the harder the pump has to work to maintain fuel pressure at the correct level. In cages, and most probably in bikes as well, running the fuel level low allows the fuel to slosh in the tank excessively and that stirs up any trash that may have found its' way into your tank, (trust me it is there), and it the gets picked up by your expensive fuel pump. In my truck I rarely run below 1/4 tank.
JMO, and what do I know anyway?
ASE Certified Master Auto Tech 1995-2005.

Hello all, I'm a past lurker on here that's slowly getting my 'feet wet'. I am grateful to all that share their knowledge here about my fav ride ever  :great:  I guess I should formally introduce myself somewhere in this forum but for now I'd like to add my perspective on this discussion on Thermodynamics and fuel pumps. It's off the topic thread started by BDF but as I understand the dynamics of heat (energy transfer) there is some incorrect but not uncommon statements regarding heat transfer here. There are also some correct ones but the explanations are off a bit. It's uncanny that everyone who chimed in is also partially correct.   :)

To summarize (paraphrase) what has been stated by Brian - it doesn't mater what is in the tank, gas or air (gas vapour) as the amount of heat generated by the pump is constant and so in a steady state situation with the energy dissipating into the environment via conduction through the tank walls  the pump is thermally unaffected by the type of medium around it. That is both true (tank temp) and false (pump temp) because the fact that we are comparing the thermal properties of a liquid and a 'gas' (air/gas vapour) as if they are the same but yet they vary significantly. A denser medium such as fuel is much more able to transfer the heat generated to the tank walls via conduction then a gas vapour can and thus does this at a lower temperature (more molecules vibrating less). This causes a much different temperature profile from the heat source to the tank wall for each medium. Where Brian is bang on is that the amount of energy dissipated to the tank walls is the same in both cases. But for the less dense gas to do the same 'work' it has to be at a higher temperature (less molecules vibrating more). That is where Mattchewn is correct, an 'empty' tank is hotter INSIDE. The exterior of the tank is not hotter however as the overall total heat dissipated is the same as Brian asserted. The hotter vapour will in fact transfer the same amount of heat to the tank walls (because there is less mass to do the work) and so the tank will NOT be hotter on the outside. These temperature variances can be very significant and even dangerous. (Thermal reactor rods losing heavy water.... oops...)

It's obvious that the same amount of energy is produced in either case, but due to the much higher mass in the fuel (heat sink) versus vapour, the fuel will be at a lower over all temperature yet holds (and transfers) the same amount of energy as the much less dense gas vapour. (Sorry if I'm repeating myself  ::)


Finally I'd like to add that this is an academic discussion only since modern pumps are designed to operate in a range of temperatures and as far as I can tell, the C-14 fuel pumps are very reliable. So this is the point where Pistole is also correct, the C-14 pump can obviously  handle the 'heat' from the pump action and from other sources.  :great:

Cheers  :beerchug:

08 Connie 14
85 Yamaha Venture
80 Kawi KZ750E
72 CB450
CDA #450
My Baby has: CB shield, Garmin w/centre mount, 2" risers, 2 Bro Carbon slip-on, Givi trunk, Visi Tech Brake light flasher, Gel pad in OEM seat, near 50,000km

Offline BDF

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The only thing worse than losing a portion of the cooling water would be to flood the reactor with cold water, slowing down more free neutrons ('moderating' them)  and ending up with a 'cold water' accident (runaway reaction). Oh wait, about the fuel pump....

Nice overview on the thermodynamics of a modern fuel pump / fuel tank. But in the end, unless a rider were actually riding the motorcycle (or any vehicle) with his / her hand inside the fuel tank, the only way to monitor the heat produced inside the tank would be to feel (and then guess the temperature) of the outside of the tank. Given those circumstances and realities, the tank temperature will not, and can not, change by varying the fuel level inside the tank given the constraints of what is producing the heat and how it is being transferred away from the fuel tank. Of course if you use a big enough field for the overall study, the entropy of the entire universe is still increasing and motorcycles are contributors....

Modern fuel pumps are of the turbine type, spin very fast and basically produce significant volume of flow with pressure being a by-product (as opposed to a positive displacement type of pump where pressure is the direct product and fluidic flow is the by- product). They are really quite simple and robust, able to pass a fair amount of debris and are almost free from shaft wear. Heat is really not a problem under any normal circumstances achievable with a modern vehicle. All of that said, they can suffer bearing wear if ran dry (out of fuel) repeatedly because it is the fuel itself that provides the function of lubrication. The really good news is that I have quite a few loose C-14 fuel pumps, pressure regulators, housings and assorted other parts and assemblies lying around. Oh wait, that is really bad news 'cause I burned up parts of them in developing this thing and had to keep buying more....

But all the way back to the main point, wanna' buy a low fuel warning eliminator / range display enabling circuit?  :D

Brian

Hello all, I'm a past lurker on here that's slowly getting my 'feet wet'. I am grateful to all that share their knowledge here about my fav ride ever  :great:  I guess I should formally introduce myself somewhere in this forum but for now I'd like to add my perspective on this discussion on Thermodynamics and fuel pumps. It's off the topic thread started by BDF but as I understand the dynamics of heat (energy transfer) there is some incorrect but not uncommon statements regarding heat transfer here. There are also some correct ones but the explanations are off a bit. It's uncanny that everyone who chimed in is also partially correct.   :)

To summarize (paraphrase) what has been stated by Brian - it doesn't mater what is in the tank, gas or air (gas vapour) as the amount of heat generated by the pump is constant and so in a steady state situation with the energy dissipating into the environment via conduction through the tank walls  the pump is thermally unaffected by the type of medium around it. That is both true (tank temp) and false (pump temp) because the fact that we are comparing the thermal properties of a liquid and a 'gas' (air/gas vapour) as if they are the same but yet they vary significantly. A denser medium such as fuel is much more able to transfer the heat generated to the tank walls via conduction then a gas vapour can and thus does this at a lower temperature (more molecules vibrating less). This causes a much different temperature profile from the heat source to the tank wall for each medium. Where Brian is bang on is that the amount of energy dissipated to the tank walls is the same in both cases. But for the less dense gas to do the same 'work' it has to be at a higher temperature (less molecules vibrating more). That is where Mattchewn is correct, an 'empty' tank is hotter INSIDE. The exterior of the tank is not hotter however as the overall total heat dissipated is the same as Brian asserted. The hotter vapour will in fact transfer the same amount of heat to the tank walls (because there is less mass to do the work) and so the tank will NOT be hotter on the outside. These temperature variances can be very significant and even dangerous. (Thermal reactor rods losing heavy water.... oops...)

It's obvious that the same amount of energy is produced in either case, but due to the much higher mass in the fuel (heat sink) versus vapour, the fuel will be at a lower over all temperature yet holds (and transfers) the same amount of energy as the much less dense gas vapour. (Sorry if I'm repeating myself  ::)


Finally I'd like to add that this is an academic discussion only since modern pumps are designed to operate in a range of temperatures and as far as I can tell, the C-14 fuel pumps are very reliable. So this is the point where Pistole is also correct, the C-14 pump can obviously  handle the 'heat' from the pump action and from other sources.  :great:

Cheers  :beerchug:
KiPass keeping you up at night? Has the low fuel warning burned your retinas? Find peace, harmony and the answer to these problems. www.incontrolne.com

Offline 4Bikes

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We might as well cover this topic completely. >:D  Does anybody know if the C-14 returns fuel back to the tank, or is it using a “Return-less” fuel system?  I think if it’s the former, it will increase heat as the fuel passes close to the engine on the fuel rails.  The heat generated in the remaining wet fuel could be more than just what is generated by the pump.
Silver 2011 C-14. Previous rides: KZ-400, KZ-750, KZ-1000.  Keep the rubber side down.  Ride Fast......Live Slow......