Adjusting Fuel Reading

Blrfl said:

Five gallons is about what's left when the sender in the upper tank hits bottom and the gauge shows two bars.

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Five gallons? I had no idea there'd be so much left at two bars. That's over half the capacity of the fuel system, so why doesn't the gauge read closer to half a tank?

Or is the gauge gauging range rather than capacity? At a conservative 30mpg that's 150miles 'till empty.

The fuel level indicator on the ST1300 may not provide a linear reading that reflects the actual fuel level, but I've always used the trip odometer to inform myself of the fuel range remaining rather than the fuel gauge. In fact I don't recall my first motorcycles having a fuel gauge. Taking into account riding conditions, solo vs two-up, headwind vs tailwind, etc. I can estimate closely enough how far I can go before looking for a a gas station. On longer trips I have my fuel stops planned to coincide with meal stops, rest stops, etc. And for the ST I take others' recommendations about not exposing the fuel pump seriously.

We all have different expectations from our motorcycles and I respect someone's need to change the way their bike works if it doesn't meet their needs. Good luck with your quest.

ST Gui said:

Five gallons? I had no idea there'd be so much left at two bars. That's over half the capacity of the fuel system, so why doesn't the gauge read closer to half a tank?

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Oops, sorry, knew what I meant and didn't write it. I corrected the post.

--Mark

Ah got it. Thanks.

For the tech's, I'll show 3 bar's for at least 50, maybe a 100 miles, to then flashing last bar with 40 or so miles.
And.
From a very full tank, bike upright and full bars I lose the right side bar within 3 miles.
Any helping thoughts would be nice.

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Dave.David said:

The upper tank has a normal fuel sending unit which of course can be bent. My fuel level loses one bar from full before I even get out of the gas station so I'm really considering doing the same myself. If there is a bad side I'm sure someone here can tell us.

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When I fill my tank all the way to the brim with the bike leaning on the side stand, when I then close the lid and turn on the ignition, the fuel gauge will usually drop one bar when I stand the bike up vertically. The only way to fill the tank completely is to put the bike on the CS first, although I seldom do that since I'm often concerned that if I only ride a few miles before parking somewhere in the sun the gas in the tank may expand enough to result in some raw fuel getting to the vapor canister. What the gauge does when the tank approaches empty is no longer a concern for me - by the time it gets down to the point that the display starts showing miles to empty in place of MPG, I know I need to fill up again - simple as that.

Don B said:

by the time it gets down to the point that the display starts showing miles to empty in place of MPG, I know I need to fill up again - simple as that.

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I'm too faint of heart to cut it that close. At three bars I'm sayin' 'Any of you boys seen a gas station around here?' At two bars I get very antsy.

I made what I felt was an amazing dead stick landing from a freeway to a gas pump in my car and I hope never to do that again.

Blrfl said:

I'll wait here for your next rant about what a bunch of junk it is 'cause I'm a helpful tech idiot.

--Mark

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Yes you are helpful,,,,thanks!

If it actually worked it might come in handy someday, although Im used by now to just going by the ODO....

But now Im depressed. This is the first thing that ever broke! :banghead:

Based on all the posts that I've seen in this thread, I haven't seen one yet that really describes a "broken" or malfunctioning fuel gauge, as in not working the way the owners manual describes. We sometimes need to pause to review what's in the book and reacquaint ourselves to the product or tool we are using, whatever that may be.
Amen

Trump said:

If it actually worked it might come in handy someday...

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It works; millions of thermistors are soaking in millions of gas tanks in pretty much everything with a low fuel indicator. It's not that the technology is bad; yours fell victim to the fact that anything manufactured by man or nature is going to have a failure rate greater than zero.

Don B said:

Based on all the posts that I've seen in this thread, I haven't seen one yet that really describes a "broken" or malfunctioning fuel gauge, as in not working the way the owners manual describes.

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I haven't seen one in 13 years other than maybe the few instances where someone took a hose to the dashboard and had the entire instrument panel go haywire. The irony is that the root causes of the failures we have seen are the same technology from the bad old days that people railing about the newfangled computerized stuff are pining for: the sensors. Once the software is right (and I'll be the first to admit that it isn't always right), the digital stuff doesn't break or wear out. When it does, it's almost always the analog parts (I'm looking at you, ST1300 knock sensors), but the real world is analog and we have to live with that.

--Mark

In 1969 we didnt even have fuel gauges (maybe) a trip meter and a reserve/main/off fuel valve. Not that I ever ran all the gas out on main.

Now with all the sensors in cars and bike if theres problems shops can charge hundreds, not change the right sensor, and you have no recourse. Just go back for more abuse.

My gauge has always been weird, I'm used to it now. But I can tell you exactly how far I can go when it gets to the low fuel setting: Exactly one mile short of the nearest gas station. Never fails.
Usually, once I get to flashing I start looking, normally between 5 and 6 gallons when I refuel.

OK ... so I ran out of fuel today. I have been having the 3 bars to flashing reserve light for a few months now. I started carrying a Primus 1.5 liter fuel bottle (for camping fuel) with me which has paid off. So .. as I started off ... I ran out of fuel. Added my 1.5 liters and got myself to a gas station (25 miles later). She only took 5.5 gallons of fuel (to the bottom of the neck). Where are my other 2 gallons of fuel (why did i run out)?

When you gas up do you put the bike on the center stand? On the center stand more gas goes in the tank and thus will read full a bit longer.

the ST doesn't really hold the 7.7 that Honda says it does. More like 7.2. Tom Austin measured the tank once for Iron Butt Rally purposes and he came up with 7.2 gal total.

jodog said:

the ST doesn't really hold the 7.7 that Honda says it does. More like 7.2. Tom Austin measured the tank once for Iron Butt Rally purposes and he came up with 7.2 gal total.

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I once put in 7.38, guessing there were just a few fumes left to run on.
A year later I managed to get 7.46 in after pushing it for over a mile. I did include re-priming the fuel pump before hanging up the nozzle.

I actually sit on the bike with it vertical (old school). Even on the side stand there wouldn't be a 2 gallon issue. Also in the past I had gotten 360 miles out of one full tank. Mostly highway and a lot of downhill. I ran out today under 250 but that is about what I normally get out of a full tank. Still confused as to why she only took 5.5 gallons. 7.0 Gallons would have been right. Double checked the tank when I got home after filling up and she was full to the neck (filled up 2 miles from home).

I'd suggest starting a new thread. Also trying opening up the lower tank and have a look in there.

I agree on the center vs side, barely any difference in the capacity. The shape of the tank doesn't hold much air in either position.

This would make a lot of sense. As I have never been able to put more than 5 gallons, immediately after the light started blinking. That would mean two things:
1. There is more than 1.2 gallons in my tank when the reserve kicks in and
2. The tank capacity is less than 7.7 gallons.

Keep in mind that if you run out of gas there is still some gas left in the tank. The fuel pick up for the fuel pump is not at the very bottom of the lower tank. The fuel capacity stated in Honda's specs probably includes the unusable gas in the lower tank.