Author Topic: Usable Fuel  (Read 672 times)

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Offline BradLH

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Usable Fuel
« on: March 13, 2019, 02:48:48 PM »
The specs for my 2018 Street glide show 6 gal fuel capacity but when the light goes on and there are only a few miles "reserve" showing I've never been able to get more than 5 gal in the tank.  Is there a gallon left in the tank at that point?

Offline fleetmechanic

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Re: Usable Fuel
« Reply #1 on: March 13, 2019, 02:54:04 PM »
The fuel pump and fuel level sensor use a small amount of the total and there is also some dead airspace in the top front area when you fill to the bottom the filler neck.

Offline PoorUB

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Re: Usable Fuel
« Reply #2 on: March 13, 2019, 05:41:52 PM »
I would say you have 6 gallons of fuel. With my 2010 I have run that well past when all the indicators said I was out of fuel. I have ridden 20-30 miles after the "low" on the miles remaining came on and still never put  six gallons in. One time I put on 5.7 gallons. If you want to be certain, toss a gallon of fuel in a saddle bag and ride it dry. You will see how many miles you can run after the gas light goes on or the "low" indication on the miles remaining.
I am an adult?? When did that happen, and how do I make it stop?!

Offline planemech

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Re: Usable Fuel
« Reply #3 on: March 13, 2019, 06:40:11 PM »
Maybe its been coincidence most every time but when I check my mileage it seems that its almost the same mpg as the number on the miles remaining when the light comes on and that number varies with how hard Im riding so maybe the light comes on when there's approximately 1 gallon left in the tank? Some of the more educated experts here might have a better answer but my buddies bike it the same way.

Offline chaos901

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Re: Usable Fuel
« Reply #4 on: March 14, 2019, 05:53:39 AM »
Really should hold about 6.2, at least that is the most I have ever put in at one time (2010 Ultra).  Riding out west and the light had been on for about 30 miles when we made a stop.  That was a one of situation traveling fast into a strong headwind that conspired to ruin to my MPG.  We do carry 1/2 gallon just in case so we were always going to make it. 

Years ago put 5.2 in a five gallon tank too. 

Offline PoorUB

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Re: Usable Fuel
« Reply #5 on: March 14, 2019, 09:20:18 AM »
It aggravates me that the gas gauge and miles remaining is ridiculously conservative. The gauge reads empty and the miles remaining on the odometer claim you are out of gas and you have a gallon left. I would prefer it was closer to reality.
I am an adult?? When did that happen, and how do I make it stop?!

Offline CndUltra88

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Re: Usable Fuel
« Reply #6 on: March 14, 2019, 11:06:16 AM »
When my idiot light would glow it was time to find some fuel.
Best I ever got was like 395kms and then I had to slosh some fuel from the other side of the tank to make it the next exit and fuel stop.
I ended up putting in 23liters in the 25liter tank.
But, as mentioned carry the spare jerry can to test your limits.
Rob
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Offline PoorUB

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Re: Usable Fuel
« Reply #7 on: March 14, 2019, 01:04:16 PM »
I ran 265 miles on my 2010 Ultra, put in 5.7 gallons. Gas gauge and miles remaining were both telling me I was screwed for many miles, but I was pretty confident I had fuel.
I am an adult?? When did that happen, and how do I make it stop?!

Offline smoserx1

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Re: Usable Fuel
« Reply #8 on: March 15, 2019, 05:20:48 AM »
It is very difficult to make a fuel gauge read accurately in a motorcycle tank due to the irregular geometric shape of the tank and the fact it is partitioned in the middle to fit over the frame backbone.  Much easier in a car with a regular shape top to bottom.  I would rather have it read empty with a gallon or more left than to still be reading something and run out.  Had a car when I was a kid that would run out with about a eighth of a tank showing on the gauge.

Offline PoorUB

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Re: Usable Fuel
« Reply #9 on: March 15, 2019, 05:43:56 AM »
It is very difficult to make a fuel gauge read accurately in a motorcycle tank due to the irregular geometric shape of the tank and the fact it is partitioned in the middle to fit over the frame backbone.  Much easier in a car with a regular shape top to bottom.  I would rather have it read empty with a gallon or more left than to still be reading something and run out.  Had a car when I was a kid that would run out with about a eighth of a tank showing on the gauge.

I can not agree with that all all.

My 2010 I took the time to bend the lever on the fuel level sensor. Took my a couple attempts to get it closer, maybe 1-2 hours spent. Someone at an engineering department and a $100,000 diploma on the wall should be able to figure it out in short order too. Regardless of the shape of the tank. More like the MoCo doesn't want too. The gas gauge is close enough, it works, it shows something resembling the fuel level in the tank and most riders will never notice.

They can't even figure out why the M8 is sumping or transferring tranny lube. Do you thing they care about a gas gauge? :hyst:


Plus, I would rather know if I have 50 miles left on the tank that there is 40 miles left, not 80. A big difference when you are fighting a head wind in the middle of Wyoming. It does me know good to have a fuel gauge that reads empty when the next gas stop is 30 miles away and I can make it without any issue. Do I start asking for fuel at farms, or keep riding? Relieves a bit of stress out of the ride. I have gotten used to knowing that when the low fuel light comes on I have a gallon to go and count my miles from there, but I shouldn't have too.
« Last Edit: March 15, 2019, 05:51:41 AM by PoorUB »
I am an adult?? When did that happen, and how do I make it stop?!

Online Hossamania

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Re: Usable Fuel
« Reply #10 on: March 15, 2019, 06:50:28 AM »
And to think, motorcycles used to be manufactured without gas gauges. How barbaric!
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Offline No Cents

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Re: Usable Fuel
« Reply #11 on: March 15, 2019, 07:41:38 AM »
And to think, motorcycles used to be manufactured without gas gauges. How barbaric!
  I don't know how many times on my old bikes I would have to remove the gas cap and rock the bike side to side to see if I could see or hear how much gas was in the tank. I'm so glad the bagger has a fuel gauge.  :teeth:
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

Offline kd

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Re: Usable Fuel
« Reply #12 on: March 15, 2019, 07:47:14 AM »
I still religiously set my trip meter (or check my mileage) when I fuel up because I don’t trust any gauges to get me there.
KD

Offline No Cents

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Re: Usable Fuel
« Reply #13 on: March 15, 2019, 07:52:33 AM »
  me too.  :embarrassed:
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

Offline PoorUB

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Re: Usable Fuel
« Reply #14 on: March 15, 2019, 08:40:20 AM »
And to think, motorcycles used to be manufactured without gas gauges. How barbaric!

LOL!

My point is if they put on on the motorcycle it should be accurate. I have a stick I  can use that is fairly accurate! :hyst:
I am an adult?? When did that happen, and how do I make it stop?!

Offline kd

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Re: Usable Fuel
« Reply #15 on: March 15, 2019, 09:16:45 AM »
I've pulled over and used a blade of grass to dip my tank when I was real worried about making the next fuel stop.
KD

Offline PoorUB

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Re: Usable Fuel
« Reply #16 on: March 15, 2019, 09:41:17 AM »
At least yhe gauge and miles remining is consistent. My low fuel light comes on with a gallon left. The light has come on within a few miles of a gas station a few times and it always takes 5 to fill it. So considering riding conditions I  get a pretty good guess on how far I can go.

Next question  is am I out at 6 gallons, or can I squeeze another quart or two in. I always think about running it out and finding out what the tank actually  holds but never get to it.
I am an adult?? When did that happen, and how do I make it stop?!

Offline SixShooter14

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Re: Usable Fuel
« Reply #17 on: March 15, 2019, 09:57:11 AM »
At least yhe gauge and miles remining is consistent. My low fuel light comes on with a gallon left. The light has come on within a few miles of a gas station a few times and it always takes 5 to fill it. So considering riding conditions I  get a pretty good guess on how far I can go.

Next question  is am I out at 6 gallons, or can I squeeze another quart or two in. I always think about running it out and finding out what the tank actually  holds but never get to it.
I ran my Softail dry twice and coasted into the station. Both times it took 5.25gal to fill.

Now, I have some aftermarket gauge on my King. I believe it's a Kury. Last night it was flashing on the red side after 130 miles. So I stopped to fill up and it only took 3.3gal. So I'm thinking it needs adjusted.
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Online Hossamania

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Re: Usable Fuel
« Reply #18 on: March 15, 2019, 10:18:45 AM »
I think I have the best of both worlds with the RK because it is carbed, has a gas gauge that is pretty accurate, and I have a petock with a half gallon reserve.
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Offline smoserx1

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Re: Usable Fuel
« Reply #19 on: March 15, 2019, 07:18:41 PM »
Quote
    It is very difficult to make a fuel gauge read accurately in a motorcycle tank due to the irregular geometric shape of the tank and the fact it is partitioned in the middle to fit over the frame backbone.  Much easier in a car with a regular shape top to bottom.  I would rather have it read empty with a gallon or more left than to still be reading something and run out.  Had a car when I was a kid that would run out with about a eighth of a tank showing on the gauge.


I can not agree with that all all.

That is fine with me if you don't agree, but the point I was making is that the sending unit has a float that measures the surface level  of the gas and this will not be an accurate analogy of the volume of liquid in a tank unless the container is vertically symmetrical, which a motorcycle tank is certainly not.  Consider a cone shaped tank.  The volume in the last third would be far less than the first third.  And yes it is possible to bend the arm of the float somewhat to maybe get the gauge to read empty when it is closer to true empty, but I am also wondering if the float hits the bottom somewhere other than the tank's lowest point.

Running out of gas is always inconvenient, bit can be dangerous in certain traffic situations.  It would not surprise me if somewhere in the annals of motorized transportation some manufacturer hasn't been sued because a vehicle ran out of gas with a gauge showing some left and the stalled vehicle was involved in an accident.  Probably why the Harley engineers design the  gauges to be somewhat conservative.

Offline PoorUB

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Re: Usable Fuel
« Reply #20 on: March 15, 2019, 08:29:10 PM »
With today's electronics it would be very simple to pour 1 gallon of liquid, measure the resistance of the sender and repeat, and engineering a electronic "curve" that would give a reasonable accurate fuel level to the gauge.

Like I said before, nobody cares that much.
I am an adult?? When did that happen, and how do I make it stop?!

Offline SixShooter14

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Re: Usable Fuel
« Reply #21 on: March 15, 2019, 09:41:52 PM »
With today's electronics it would be very simple to pour 1 gallon of liquid, measure the resistance of the sender and repeat, and engineering a electronic "curve" that would give a reasonable accurate fuel level to the gauge.

Like I said before, nobody cares that much.
:agree: Both statements there are very true. It would not be difficult for the gauge to be calibrated with a volume curve based on the tank contour. But whether it is done or whether anyone wants to try recalibrating it after the fact is pretty unlikely.
'97 Road King, Rinehart True Dual, Mikuni carb

Offline bump

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Re: Usable Fuel
« Reply #22 on: March 16, 2019, 03:52:10 AM »
Quote
    It is very difficult to make a fuel gauge read accurately in a motorcycle tank due to the irregular geometric shape of the tank and the fact it is partitioned in the middle to fit over the frame backbone.  Much easier in a car with a regular shape top to bottom.  I would rather have it read empty with a gallon or more left than to still be reading something and run out.  Had a car when I was a kid that would run out with about a eighth of a tank showing on the gauge.

I myself want a gas gauge that shows half a tank when 2.5 gallons in a 5 gallon is left.
Don't care what shape the is.

I can not agree with that all all.

That is fine with me if you don't agree, but the point I was making is that the sending unit has a float that measures the surface level  of the gas and this will not be an accurate analogy of the volume of liquid in a tank unless the container is vertically symmetrical, which a motorcycle tank is certainly not.  Consider a cone shaped tank.  The volume in the last third would be far less than the first third.  And yes it is possible to bend the arm of the float somewhat to maybe get the gauge to read empty when it is closer to true empty, but I am also wondering if the float hits the bottom somewhere other than the tank's lowest point.

Running out of gas is always inconvenient, bit can be dangerous in certain traffic situations.  It would not surprise me if somewhere in the annals of motorized transportation some manufacturer hasn't been sued because a vehicle ran out of gas with a gauge showing some left and the stalled vehicle was involved in an accident.  Probably why the Harley engineers design the  gauges to be somewhat conservative.

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Re: Usable Fuel
« Reply #23 on: March 16, 2019, 05:19:14 AM »
I've never relied completely on the gas gauge, I always set the odometer when the tank is filled, the gauge is just a nice visual. As far as using it to get the last mile out of the tank, I don't, I just get gas when it's close, usually with about 1/4 tank left, or my normal mileage range. Why push it? On trips, I like to start thinking about a fill once it gets to half a tank, just in case I get caught out in an area that doesn't have a lot of stations. If I run out of gas because I wasn't paying attention, sometimes that happens. If I run out of gas because I was pushing it too far on purpose, passing stations when I should not have, then I'm an idiot.
I never understood the guys that show up for a day long ride without a full tank of gas. I've had friends show up with less than half a tank and need gas right away because we've been riding hard for a whole 50 miles. Or they show up at the beginning of the ride and say they need gas before we even start. Frustrating.
On long trips with friends, our gas stops are determined by our pee stops, which come long before the gas tanks run low, so no danger of running out.
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Offline Rusticwater

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Re: Usable Fuel
« Reply #24 on: March 16, 2019, 05:26:37 AM »
Remember that the gas tanks, generally speaking, were designed back in the days of carburetors and you had a fuel shutoff valve that also had a “reserve” position. The valve, which was also the fuel pickup, was usually located at the rear of the tank, the lowest level.

On my current ‘10 FXDC, the internal fuel pickup is more towards the front of the tank. Before I changed my fuel filter I ran the fuel down as low as I dared close to home. When I took the tank internals apart I realized that under normal circumstances I could not run the tank “totally dry” because the fuel pickup was slightly higher than the rear of the tank.

Having the EFI fuel line exit the rear of the tank is for looks only, or probably to save retooling costs when Harley switched to EFI. Since it’s pressure fed and not gravity fed, it could exit anywhere on the tank.

Things like suspension, having a tank lift, payload, etc. are all going to affect the angle of the tank and therefore the usable fuel level relative to the fuel pickup.
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