Adjusting Fuel Reading

T_C · Jun 4, 2017

etalors said:
Ok here is my data for this week. Reserve kicked in after 240 miles of city

What's a reserve? I had some older bikes without a fuel gauge that had a reserve tank or they had two separate pick-ups in the main. But The ST, nope. Upper tank and lower tank, but no reserve.

If you mean the flashy gas gauge?? It just signifies 1.2 gallons left, but same tank as always.
Suggested it before, I'll suggest again. Check hoses between upper/lower.

etalors · Jun 4, 2017

T_C said:
What's a reserve? I had some older bikes without a fuel gauge that had a reserve tank or they had two separate pick

You are correct sir, I meant the flashing gauge. As for checking the hoses. I did not see any problems. The overall mileage was ok (IMO). Did you see any mechanical issues with wha t I wrote.

st1300r · Jun 4, 2017

etalors said:
Ok here is my data for this week. Reserve kicked in after 240 miles of city driving. The miles remaining went down gradually (no abnormalities this time). With 24 miles of gas remaining per the display, I stopped and filled up to the neck with 6.89gallons. If the display is to be assumed somewhat accurate, that would mean about half a gallon of usable gas left in the tank. I doubt that I would have gone 24 miles. Although I was tempted to. I rode 40 miles in reserve.

That sounds about right.

Mr Blrfl has a thread on here somewhere describing the brain box interpretation of the 2 sensors and estimation when it only has the injector pulses for data. iirc correctly the guessing starts with a hot thermistor and last 20 min prior average mpg. Since you tend back off the wick when the confuser notices the 2nd sensor can't give any more warning, you can see the miles to pushing number go up as your burn rate went down down. Its 1st guess, for me, is usually about 52miles. [-]If you key off at some point during the guessing, I *think the confuser does not store its last guess and looses its reference, otoh it already gave you fair warning.[/-]

T_C · Jun 5, 2017

st1300r said:
That sounds about righ. [...]If you key off at some point during the guessing, I *think the confuser does not store its last guess and looses its reference, otoh it already gave you fair warning.

It doesn't forget on key-off. However, setting the bike on the side-stand and then when you remount and quickly standing it back up might splash fuel up the sidewalls touching the sensor of the lower tank and make the puter think you added more fuel so it resets the countdown back to the 1.2 gallon threshold.

I have quite a bit of experience here, my daily commute often has me arriving at work just around the time my blinky fuel gauge starts. I don't like to buy gas in the next over state, so I push it as there are no gas stations easily accessed on my morning commute. If I blink before I geg to work I am gentle on the parking and throttle.

etalors · Jun 5, 2017

Just getting a consensus on what is the approximate distance folks travel on the hwy before the light starts flashing. Mine has been 280 miles. But I expect that to increase this year since I replaced the tstat.

Blrfl · Jun 5, 2017

st1300r said:
Mr Blrfl has a thread on here somewhere describing the brain box interpretation of the 2 sensors and estimation when it only has the injector pulses for data.

That would be here: http://stwiki.notonthe.net/twiki/bin/view/ST13/FuelGauge

TL;DR: Two bars is where you start thinking about where you're going to get gas and one bar is where you need to be on the way there. The only diff between this bike and older ones is that you don't have to reach down and flip the petcock to reserve when the engine sputters out at an inopportune time.

--Mark

st1300r · Jun 5, 2017

Many moons ago I discovered the possibility of leaving the petcock on reserve after a fill... derp.

Scooter · Jun 7, 2017

T_C said:
It doesn't forget on key-off. However, setting the bike on the side-stand and then when you remount and quickly standing it back up might splash fuel up the sidewalls touching the sensor of the lower tank and make the puter think you added more fuel so it resets the countdown back to the 1.2 gallon threshold.

I have quite a bit of experience here, my daily commute often has me arriving at work just around the time my blinky fuel gauge starts. I don't like to buy gas in the next over state, so I push it as there are no gas stations easily accessed on my morning commute. If I blink before I geg to work I am gentle on the parking and throttle.

IMHO and experience I think it does forget on key off. Or at least it forgets something. The thermistor is enclosed in a metal can so splashing some fuel on it isn't going to automatically reset the counter. I would also think that a properly written algorithm could account for rapidly changing values that might indicate splashing fuel on that sensor.

What we really need is for somebody to step up and run their tank down to the point where it starts flashing, pull the pump and wrap up the lower sensor so we know it can't get any fuel splashed on it. Any takers???

T_C · Jun 8, 2017

Scooter said:
What we really need is for somebody to step up and run their tank down to the point where it starts flashing, pull the pump and wrap up the lower sensor so we know it can't get any fuel splashed on it. Any takers???

Or you could do the opposite. Run it down to 30 miles showing... stop, turn bike on/off a couple of times. See if it resets. Next, rock the bike back and forth, see if it resets. In fact.. my bike is sitting in the parking lot outside my building with a flashy bar showing... I could test... but then I'm not guaranteed to be an impartial opinion.

etalors · Jun 8, 2017

Here is my question as this thread is getting confusing with all the info.
Is the 1.3 gallon of gas remaining when the flasher comes on, all usable or is some of it designed to remain in the lower tank to keep the pump submerged etc. In other words is there still gas left in the lower tank which cannot be pumped to the engine. If so, the how much is it.

W0QNX · Jun 8, 2017

etalors said:
Just getting a consensus on what is the approximate distance folks travel on the hwy before the light starts flashing. Mine has been 280 miles. But I expect that to increase this year since I replaced the tstat.

There is no normal, uphill downhill intothewind downwind 45 mph or 78 mph? yeah I do average 78 mph on some tanks and those make it to 250 going downwind.

etalors said:
Here is my question as this thread is getting confusing with all the info.
Is the 1.3 gallon of gas remaining when the flasher comes on, all usable or is some of it designed to remain in the lower tank to keep the pump submerged etc. In other words is there still gas left in the lower tank which cannot be pumped to the engine. If so, the how much is it.

1.3 gallons is not all useable. probably about 1.15 is usable. The pump pickup sits almost right on the bottom of the tank in a nice pretty little filter wrapper thingy attached to the very bottom of the pump. So go for it, use all 1.15 gallons bro but at 1.16 you'll be pushing.

etalors · Jun 9, 2017

ZIAMON said:
There is no normal, uphill downhill intothewind downwind 45 mph or 78 mph? yeah I do average 78 mph on some tanks and those make it to 250 going downwind.
I have routinely gotten round 280 on the hwy before getting the warning flashing.

1.3 gallons is not all useable. probably about 1.15 is usable. The pump pickup sits almost right on the bottom of the tank in a nice pretty little filter wrapper thingy attached to the very bottom of the pump. So go for it, use all 1.15 gallons bro but at 1.16 you'll be pushing.

This would mean that if I immediately fill up after I get the flashing, I should be able to put in roughly 6.3-6.4 gallons, since, 7.7-1.3=6.4. However, I have never been able to fill more than 5.8 at that point. And I mean filling all the way almost into the neck on the center stand. I'm puzzled !!

Blrfl · Jun 9, 2017

etalors said:
...I have never been able to fill more than 5.8 at that point.

5.8 is a bit more than the capacity of the upper tank. What kind of shape is your joint hose in?

--Mark

etalors · Jun 9, 2017

Blrfl said:
5.8 is a bit more than the capacity of the upper tank. What kind of shape is your joint hose in?

When the warning starts flashing, we have already used up part of the lower tank. So 5.8 is not all going into the upper tank. some goes to the lower tank as well. That is not my question. My question was that right at the time the warning come on, I should be able to fill about 6.3 gallons. But I am only able to fill about 5.8. (7.7-1.3)=6.4

nt650hawk · Jun 9, 2017

had 20 miles flicking at me and added 7 gallons yesterday

etalors · Jun 9, 2017

nt650hawk said:
had 20 miles flicking at me and added 7 gallons yesterday

Had 24 miles flashing at me and I filled 6.875 gallons

etalors · Jun 9, 2017

nt650hawk said:
had 20 miles flicking at me and added 7 gallons yesterday

My feeling is that even if the engine stops due to lack of gas, I will not be able to fill 7.67 gallons.

T_C · Jun 9, 2017

etalors said:
My feeling is that even if the engine stops due to lack of gas, I will not be able to fill 7.67 gallons.

Mine stopped and I put in 7.47.

I don't recommend you trying to get that far... I had to push the bike to get it, literally, I pushed it over a mile, uphill for a bit, full gear...
7.38 is the most I put in without having to push the bike up to the gas pump.

jonjonboo · Jun 9, 2017

No two bikes will be exactly the same, I have ran out of gas and filled bike up with 6.8 gallons once. Then another time I had to ride bike until I found a gas station with almost zero miles left flashing and I squeezed in 7.2 gallons. Perhaps some gas pump meters are jacking us around ?? What I do now is when the low fuel begins to flash I look for fuel within 30 miles to be safe.

BakerBoy · Jun 9, 2017

Maximum fuel volume is somewhere in the 7.2 to 7.4 gallons range as reported by many who've run out of gas.

Honda's 7.7 gallon claim just isn't accurate--perhaps they computed volume without fuel float and fuel pump assembly in the tanks.

On mine, I recall the maximum I ever put in was about 7.1 gallons with a handful of miles still on the countdown display. It was not a comfortable feeling the last few miles!

Adjusting Fuel Reading

T_C

etalors

st1300r

T_C

etalors

Blrfl

Natural Rider Enhancement

st1300r

Scooter

This space for rent...

T_C

etalors

W0QNX

Blacksheep Tribal Member

etalors

Blrfl

Natural Rider Enhancement

etalors

nt650hawk

Gino

etalors

etalors

T_C

jonjonboo

BakerBoy

It's all small stuff.