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Fuel gauge fluctuating at full


vango

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Sounds like the sending unit is sticking, or its not plugged in securely...
Before I dive in....would you know whereabouts of that connection (under tank)?
From the cruise control install instructions: 4470202.jpg
 
 
 
A government which robs Peter to pay Paul can always depend on the support of Paul.
George Bernard Shaw (1856-1950)
Bikes:
2015 FJ-09, Seat Concepts seat cover and foam, Cal Sci medium screen, rim stripes, factory heated grips, Cortech Dryver tank bag ring, Modified stock exhaust, FlashTune with Graves fuel map, Cree driving lights, Aux power socket.
2012 Street Triple type R (Wifes)
2007 FJR1300 (Sold!)
 
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I fill my bike full and after about 10km it drops to half tank then randomly it jumps to full and then randomly back to half. Any ideas what could cause this ?
 
Same thing here, just noticed that yesterday....
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  • 1 month later...
Ya mine definitely doesn't work at the top end at all. It never shows a full tank . Its stuck at half tank. If it does show full , it usually blips back to a half a tank after a few seconds. It still works as I run down on fuel it goes down , but irritating. I pulled the tank. Checked the connection. Seemed fine. Any ideas ?
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Only thing you can do from here is tear into it. Remove the tank, drain it, flip it upside down, remove the fuel pump assy and test the sending unit. To test the sending unit you move the arm gently through its full range, monitoring the resistance measurements. Specs are in the service manual. If it's in the full position and the resistance is way off, you are looking at a new fuel pump assy and gasket.
 
The only other wrinkle here, is that if there is too much resistance in the wiring between the sending unit and the Instrument Cluster - then the sending unit is fine and you have a bad/dirty connection somewhere.
 
My guess is the sending unit has either failed when full, or its sticking for some reason.
 
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  • 4 months later...
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My new in July 2016 Red 2015 FJ-09 averages about 41 ~ 43 mpg on our crappy 91 octane E10 fuel and the gas gauge was fairly accurate and ran down normally until recently (at about 5,300 miles) when it started sticking on full until about 105 miles then suddenly dropping to half full where it should be approximately. This has occurred over the last 4 or so fill ups except for one when I filled up and the gauge was stuck at about half way then suddenly went to full and then did the usual stick until 105 miles thing. Weird. I've run as far as 21 miles on the blinking empty light count-down and get about 2 mpg less than the mpg indicated.
 
Gas_Gage_stuck_on_full_until_100_miles.jpg
 
2016_09_25_Fuel_Gage_Right_After_Fill_Up.jpg
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My fz-07 does the same thing in the summer time reads a bar higher in sunlight and 1 bar less in cool weather...still get very similar total miles per tank...I go by mileage rather than rely on the fuel gauge...it's just a quick reference for me...gauges can be off as much as 10% from factory...
2012 wr250f - C-class 30+ age group
2015 fz-07- Hordpower Edition-80whp
2015 fj-09- Graves Exhaust w/Woolich tune by 2WDW @120whp
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It is normal to show half after fill up and then jump up to full 5 miles later?
 
Not that's not normal. Mine will reset to full right as I'm pulling out of the gas station. To jump to half after around 100 miles is. There is no three quarter full mark which I don't like but then again I go by math and my trip meter on all my motorcycles.
A Motorcyclist's Church is the open road....
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when it started sticking on full until about 105 miles then suddenly dropping to half full where it should be approximately.
 
Yes this is normal for the bike. Sucks, but lots of us have it.
 

I filled up and the gauge was stuck at about half way then suddenly went to full and then did the usual stick until 105 miles thing
 
My experience - if mine sits on a sidestand overnight, it will sometimes show a lower bar reading then jump up after several miles. The bike isn't just filled up but it's dozens of miles above the lower bar.
 

...get about 2 mpg less than the mpg indicated.
 
Mileage reading is about 5% optimistic. Sounds consistent with others reports.
 
These AREN'T as accurate as car fuel gauges (not that those are particularly accurate).
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