Gas guage only shows 3 bars all the time

sethhuner

Joined
May 16, 2025
Messages
13
Age
38
Location
Kentucky
Bike
ST1300
I filled it up with fuel and it still only shows 3 bars. I replaced the battery and that didn't reset it it still shows 3 bars. What should I do becuase I would really like the guage to work right. How much do you think this might cost to get fixed? Google says maybe that i would have to even get the fuel pump replaced as well as the sending unit. Any tips?

Thanks a lot in advance.
 
ps. i think i bled the brakes right and am working on replacing the coolant. just need to replace brake pads and tires too. THis bike sat for 4 years before i bought it and previous owner told me about the fuel guage issue upon meeting up to purchase it.
 
sethhuner said:
I filled it up with fuel and it still only shows 3 bars. I replaced the battery and that didn't reset it it still shows 3 bars. What should I do becuase I would really like the guage to work right. How much do you think this might cost to get fixed? Google says maybe that i would have to even get the fuel pump replaced as well as the sending unit. Any tips?

Thanks a lot in advance.
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FWIW, same with mine when I bought it. But after sitting with Marvel Mistery Oil added to the tank over the winter, the display started showing signs of life again. Gave it one more shot of MMO, and the gauge has improved to the point where it is useful again.

Don't ask me why!
 
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Send Igofar a PM w/ your phone number. You cannot get better advice anywhere on how to fix your bike.
 
It's an easy job to remove the fuel level sensor and clean the contacts, and a good time to replace the fuel line from the top tank to the bottom tank as well. Remember to get a new seal for the fuel sender unit before removing it.
 
On ST13 there are two tanks and two tank sensors.

3 bars would be consistent with upper tank sensor being stuck in empty position.

Should go below 3 bars after top tank is empty and sensor in lower tank starts to move.
 
V4 Rider said:
On ST13 there are two tanks and two tank sensors.

3 bars would be consistent with upper tank sensor being stuck in empty position.

Should go below 3 bars after top tank is empty and sensor in lower tank starts to move.
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There are two fuel level sensors in the ST1300 fuel system. The moveable one is in the upper tank and controls the fuel gauge segments. The second sensor is for the low fuel warning. This is a thermistor that does not move and is in the lower tank.
 
sethhuner said:
What should I do becuase I would really like the guage to work right.
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I had some fuel gage/sender issues at the beginning of this season. I had left the upper tank dry, from last fall,, as I intended to do do some F/I work in the spring,, on my 2012 ST13. Big mistake !! Now, this bike has always had a slowly climbing gage,,, when the tank is filled from 2 or 3 bars. Especially if it has sat overnight, or longer. The gage might take 5 minutes of riding to register 8 bars.,,, coming up from 2 or 3 bars before filling. Also,, in the spring,,, the mileage calculator refused to function. All manner of cleaners and solvents only managed to revive the mileage calculator, eventually. And while occasionally the 8-bar level indicator would show signs of more normal function,, that would not last long. I eventually pulled the sender and gave it the white rubber pencil eraser treatment. That worked,,, but the gage is still slow to respond to a tank up. Next time the sender is out,, another one will go in, in it's place. But for now,,, I just put the bike away full. A couple of other observations are,,, that I treat my 2004 pretty much the same,,, and do not have these behaviors from it. And two,,, the wet electrical connections on the sender are solid. So keep an eye out for a replacement sending unit. I am,,,,, cheers,, CAt'
 
update to post #12,,,, last Tuesday,,, I ran my 2012's fuel level down to just under 3 bars,,,, so lets say %33 of it's 29L capacity,,, which would be about 9.5L of fuel onboard. So given that about 8L sits in the lower tank,,, that means there was only 1.5L in the upper tank,, approximately. So, then the bike sat for a week,, while I was riding other things,,, until I gassed it up for this Tuesdays evening ride. After filling the bike full,,, it took nearly 20 minutes of riding for the indicator to incrementally climb to all 8 bars. And after it did reach a full 8 bars,,, the indicator began to function normally. Something prevents the sender from doing it's thing,,, after the sender has been "left to dry out" for a significant period of time. Bizzare, huh ? Well, whatever,,, a replacement sender is on my xmas list,,, cheers,,, CAt'
 
This might be time to try some fuel injection cleaner in the full tank; it might help to clean up the contacts on the fuel sender unit. I assume that leaving the sender dry has allowed some sort of varnish to form that has reduced conductivity or introduced some stickiness to the action of the float arm.
 
It doesn't seem to have anything to do with the electrical side of the system because the gauge will eventually read full. This would seem to indicate that the electrical portion of the system is working as it should. For some reason the float arm is taking to long to get to the full position. The below is a photo that I nipped from Larry. It shows how the float arm moves on a pivot point to move the electrical contact through its range of motion. Assuming that there is nothing in the tank that is causing an obstruction, maybe there is to much resistance to movement of the float arm in its pivot point for some reason.

1761107340061.jpeg
 
TerryS said:
This might be time to try some fuel injection cleaner in the full tank; it might help to clean up the contacts on the fuel sender unit. I assume that leaving the sender dry has allowed some sort of varnish to form that has reduced conductivity or introduced some stickiness to the action of the float arm.
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Marvel Mystery Oil helped with that on my ST with similar symptoms.
 
TerryS said:
This might be time to try some fuel injection cleaner in the full tank; it might help to clean up the contacts on the fuel sender unit. I assume that leaving the sender dry has allowed some sort of varnish to form that has reduced conductivity or introduced some stickiness to the action of the float arm.
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all good points, Terry,, but as per previous posts, I ran many tanks with many different solvents and cleaners. They did revive the mileage calculator function,,, but did not cure the sender related issue. I also performed the recommend manual cleaning of the senders contacts. The bikes been sitting fully fueled through this 5 day rainy spell,,, and I know it will function normally on the weekend !! CAt'
 
MidLife said:
Marvel Mystery Oil helped with that on my ST with similar symptoms.
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used it,,, and Seafoam,,, and Gum Out,,, and Lucas,,, and others. Both by soaking for days and also concentrated while riding. Didn't help the level indicator function. Next time the senders contacts dried out,,, they got lazy again. MMO,,, great stuff = kerosene + 11 different herbs and spices !! LOL,, CAt'
 
Andrew Shadow said:
Assuming that there is nothing in the tank that is causing an obstruction, maybe there is to much resistance to movement of the float arm in its pivot point for some reason.
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That's the sender, Andrew,,, thanks. Seems to move very freely,,, if anything too freely,, perhaps breaking contact in places,, when dry. If that's the case,,, then the fix is still to replace it, having tried the cleaning options. cheers, CAt'

ps: funny that my 2004 doesn't show this tendency after 260k km's,,, while the 2012 has 169k km's
 
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