Fuel gauge off

[edgar]

Ok so I've been meaning to ask here for awhile now but I always forget. So my FZ (2015) was purchased used, seller wasn't completely honest with me, surprise surprise, and I found that all the wiring behind the headlight has been cut up and crimped back together. I'm assuming he effed up the headlight and Mickey Moused it all back together but who knows. Anyway, the fuel gauge has always been off. For example today I had only one bar left in the fuel gauge but when I put gas in it, it only fit 1.3 gallons. Obviously we know it's a 3 gallon tank so you can see the issue here. I'm preparing to take some longer rides as the spring comes so I want this taken care of
 
Where do I start? What do I look at/replace. I'm not a mechanic but I can do basic things and have a decent amount of tools. Any help is GREATLY appreciated

[Guest]

I bought my bike brand new and I've noticed that when I drop into the f mode and get to the pump I fill up gas to the rim of the tank and I'm only able to fill up like 2.4 gallons.. Not sure if all fz's are like that or if I have an issue.. Soo I assume one can do 50+miles in f mode if there is soo much fuel in "reserve"

[norcal616]

When the F starts flashing and the trip counter shows x amount of miles on E thats when your on reserve...general consensus seems to be about 25-30 miles on the flashing F... I tend to ignore the fuel guage.. I go by miles i rack up and then check where the fuel is when im near my limit

[SkH]

You want an off fuel gauge, get a Kawasaki. Haha. Hmm... 4.5 gallon tank (my kawasaki), I'm on my last bar. *goes to gas station, puts in 1.5 and its full*
 
Anyway, I have 3 bikes, all 3 have what I would call a guestimate fuel gauge. In other words, unreliable. Yeah, best to reset your trip meter everytime you fill up and go mainly by that if you want a more accurate read. If not, then psychologically you have to teach yourself that when you have one bar, that it basically means you have "2 bars" instead. Because when you actually reach the point where it starts flashing F trip, you have a little less than 1 gallon of gas left which is still a lot.

[edgar]

Ok so this is something that generally happens with most bikes then? This is my first "real bike," I came from a ruckus and grom which were surprisingly accurate in the fuel gauge. I don't know, I just think that the fuel gauge being on the last tick and me still having 2 gallons in the tank is pretty far off haha. I suppose I could just go off my trip meter. We're supposed to get roughly 150 miles out of the tank right?

[duenan]

Ok so this is something that generally happens with most bikes then? This is my first "real bike," I came from a ruckus and grom which were surprisingly accurate in the fuel gauge. I don't know, I just think that the fuel gauge being on the last tick and me still having 2 gallons in the tank is pretty far off haha. I suppose I could just go off my trip meter. We're supposed to get roughly 150 miles out of the tank right?

Do either of those have an F trip?  A set amount of fuel set aside for reserve, and once you hit that reserve, the fuel gauge notifies you that you are on reserves?
 
Any bike that has an f trip indicator will seemingly seem off on its gauge.  You need to account for the F trip and adjust accordingly.  The only way you'll fully understand is keep riding until your fuel gauge starts blinking and it begins a 0.0 mileage indicator.  And then ride some more.  Ride at least another 15 miles.  THEN you fill up your tank.  Do this a few times, or even once, and keep that aspect of the bike in mind, then you'll understand that one bar isn't really one bar.  And you can learn to ignore being on one bar.  And also you can just ignore the fuel gauge altogether and gas the bike whenever and only pay attention to the gauge when it starts blinking and the 0.0 miles indicator starts going up.
 
If a bike doesn't have an f trip, then the fuel gauge will seem more accurate, but then you have to be on point with going to the gas station when it hits one bar.
 

[rick]

Ok so this is something that generally happens with most bikes then? This is my first "real bike," I came from a ruckus and grom which were surprisingly accurate in the fuel gauge. I don't know, I just think that the fuel gauge being on the last tick and me still having 2 gallons in the tank is pretty far off haha. I suppose I could just go off my trip meter. We're supposed to get roughly 150 miles out of the tank right?

Yer basing that on the specs for a full tank. I think you'll find that Yamaha was a bit, erm, optimistic listing a 3.7 gallon capacity. 3.4 gallons (maybe even 3.3) is probably more accurate.  
With such a small tank, you to get a feel for how much is left at a specific gauge reading - don't expect it to be liner as the inside of the tank is not. My Futura will use 2 + gallons of it's 5.3 gallon capacity before the gauge no longer reads Full. 
 
You should easily be able to see 60+ mpg if you are gentle on the throttle. I saw 72 mpg on one tankful while I was keeping revs down early on. Even with revs well up in 3rd and 4th gear on one ride last summer, I saw 65mpg.  It's sorta surreal - and frankly, hard to get used to - going nearly 200 miles and using so little fuel.
 
Who knows what was done with your wiring loom. But I'd think you'd have no fuel gauge at all if the wires were not reconnected. 
 
 
 
 
 

[edgar]

Ok so this is something that generally happens with most bikes then? This is my first "real bike," I came from a ruckus and grom which were surprisingly accurate in the fuel gauge. I don't know, I just think that the fuel gauge being on the last tick and me still having 2 gallons in the tank is pretty far off haha. I suppose I could just go off my trip meter. We're supposed to get roughly 150 miles out of the tank right?

Yer basing that on the specs for a full tank. I think you'll find that Yamaha was a bit, erm, optimistic listing a 3.7 gallon capacity. 3.4 gallons (maybe even 3.3) is probably more accurate.  
With such a small tank, you to get a feel for how much is left at a specific gauge reading - don't expect it to be liner as the inside of the tank is not. My Futura will use 2 + gallons of it's 5.3 gallon capacity before the gauge no longer reads Full. 
 
You should easily be able to see 60+ mpg if you are gentle on the throttle. I saw 72 mpg on one tankful while I was keeping revs down early on. Even with revs well up in 3rd and 4th gear on one ride last summer, I saw 65mpg.  It's sorta surreal - and frankly, hard to get used to - going nearly 200 miles and using so little fuel.
 
Who knows what was done with your wiring loom. But I'd think you'd have no fuel gauge at all if the wires were not reconnected. 
 
 
 
 

 
 
Ok, thanks guys. I'll be basing it off the trip monitor and then hurry my ass up to a gas station when I hit the yellow fuel light

[mjh937]

@edgar, unless it has been changed since I got mine there is no low fuel light. The fuel gauge will start flashing and the f range will start counting up from zero miles when you reach the reserve fuel level. Waiting for a light will be a bad idea

[firstyammerha]

This is a big subject over on the FZ07 page of the FZ09.org site. It's worth checking out. My personal experience with my 5 month old 2016 with 200 miles on the clock was 120 miles when I filled it up first time. 2.4 gallons to the base of the filler tube. I'm riding by the break in instructions around town. The low fuel light came on a few days ago and I'm going to ride this tank to a 40 mile reading on the range remaining readout.Fill it up again and see what how much it holds then. I'll continue this until I get a reading that's consistent and reliable. I had an FZ09 before this bike and I believe the range to reserve was about the same. At least now I'm not buying premium gas.

[duenan]

When I was discussing this with my buddy who owns a BMW gs1200, he was telling me the widespread issue with that particular bike is you actually run out of gas even though the gauge still has bars (usually more than one bar).
 
I mean, even a BMW motorcycle has bad fuel gauge indicators, that pretty much tells you everything you need to know.

[rick]

I mean, even a BMW motorcycle has bad fuel gauge indicators, that pretty much tells you everything you need to know.

After owning 3 BMWs, over a span of nearly 3 decades, I'd be less likely to make them the std. to judge by.  
BMWs still have their fair share (if not more) of shall we say "issues". One thing is certain though, no matter how many bikes get broken by an "issue", the factory will rarely, if ever, admit it was done wrong - even if they redesign it a couple years later. 
 
And here's my version of everything you need to know. The Rotor powered Aprilia I've owned since 2003 has been far more reliable than any of those 3 BMWs. 

[duenan]

I mean, even a BMW motorcycle has bad fuel gauge indicators, that pretty much tells you everything you need to know.

After owning 3 BMWs, over a span of nearly 3 decades, I'd be less likely to make them the std. to judge by.  
BMWs still have their fair share (if not more) of shall we say "issues". One thing is certain though, no matter how many bikes get broken by an "issue", the factory will rarely, if ever, admit it was done wrong - even if they redesign it a couple years later. 
 
And here's my version of everything you need to know. The Rotor powered Aprilia I've owned since 2003 has been far more reliable than any of those 3 BMWs. 

I agree with you, BMWs aren't the most reliable but I was more or less using them in regards to technological precision.  Because in that instance, the gauge was functioning normally.  It wasn't broken.  That's just how off the gauge was.  And if the fuel gauge of a technology/precision inclined motor company doesn't work so well what can you expect from any other company? 

[rick]

My last BMW, a beautiful K1100RSA in black and silver was built missing locating dowels inside the cylinder head that fixed the front cam journals square to the cam shafts. Those journals are hand fit and worn badly at only 15k miles. At around 8k miles, the radiator fan slipped off its shaft and drilled a hole into the back of the radiator(dealer said he'd never seen that before - turns out it was common), at 4 k miles the front brake pads were toast. The ABS only scared me when the roads were dry and in 8 years never once activated in the wet.
 
That motor blew up on the next guy.
 
- so much for technological precision.
 
The problem with these fuel gauges is twofold - one is the shape of the tank and the other is the mere size of these gas tanks. With the tank not having a "linear" shape, it's hard to make any fuel gauge work properly. And with the tank being small, any error gets magnified.
 
That said, when the go get gas warning light comes on my Futura's dash, there's always 1.0 gallons left, even if it refuses to read Full sometimes when it most certainly is.

[firstyammerha]

Last night, I decided not to push my luck riding around with the flashing fuel gauge so I filled her up. The trip meter showed 29.8 miles on the reserve and a total of 163 miles for that tank. The bike took 3.16 gallons to bring the fuel level to the bottom of the filler tube. I'm riding on the break in schedule around town. Another 300 miles will raise my rpm limit to 6000 so I'll be able to comfortably use the freeway.

[mcbrien]

I to am in brake in mode. went 190 miles and added 2.83 gallons. I was 14 miles into reserve and getting nervous.Guess I'll be able to do 200 miles ! I will carry spare gas soon to see how far reserve really goes. My tenere willgo 40 miles on reserve.

[skyway6]

I picked up a 2017 FZ-07 on April 15/ The fuel gauge thing was the first i noticed. Something to get used to i guess.
When i saw the last bar i stopped to fill up. Tank was just under half full. Only put in approx 8liters (of 14).
 
I guess the main thing to get used to is how far to trust the F range indicator. If the bars indicator is not accurate,
how far do we trust the xx liters to empty F gauge?

[modene]

I picked up a 2017 FZ-07 on April 15/ The fuel gauge thing was the first i noticed. Something to get used to i guess. When i saw the last bar i stopped to fill up. Tank was just under half full. Only put in approx 8liters (of 14).
 
I guess the main thing to get used to is how far to trust the F range indicator. If the bars indicator is not accurate,
how far do we trust the xx liters to empty F gauge?

Set your trip meter & estimate average 50mpg that will get you in the ballpark of how many gallons you used

[rick]

I picked up a 2017 FZ-07 on April 15/ The fuel gauge thing was the first i noticed. Something to get used to i guess. When i saw the last bar i stopped to fill up. Tank was just under half full. Only put in approx 8liters (of 14).
 
I guess the main thing to get used to is how far to trust the F range indicator. If the bars indicator is not accurate,
how far do we trust the xx liters to empty F gauge?

I'm not convinced you can actually get 14 liters (3.7 gallons) in the tank. I'm thinking it's more like 12.5 (3.3 gallons) or maybe even closer to 12 liters. 
Just run the thing until the gauge starts blinking, then go get fuel and see how much it takes to filll to the bottom of that metal plate. The reserve is claimed to be 2.7 liters (0.7 gallons), but who knows how accurate that is. 
 
Don't think I've ever put in much more than 2.6 gallons following this.
 
I suspect Yamaha measures the tank "volume" mathematically (hmm, 3 dimensional calculus) . It might not include the space the pump assembly occupies or account for their recommendation to stop short of the tank being full to the top. 
 
The good news is that this motor will return into the 70 mpg range if you are gentile with the throttle. 

[faffi]

I'm pretty sure the fuel tank holds 14 litres - German magazines usually test manufacturer claims.
 
This forum had some interesting information - warning, it's in German! http://www.mt07-forum.de/reichweite-400.html
 
One ran his tank dry and managed to get 13.27 litres in. Before the engine stopped it had been missing for the last 5 km.
 
One theory is that there was more gas left on the side of the tank without an outlet. At least that was common with older bikes; tip the bike over on its side to get the fuel over where it can be used.
 
Another theory is that it takes time to fill the tank completely. Fill up, wait ten seconds, fill a bit more. Repeat 4-5 times.
 
One rider rode until the engine began to miss and got 12.78 litres in.
 
Another claimed he had ridden 330 km without running dry, with the computer saying between 4.2 and 4.6 l/100km consumption. That would be between 13.86 and 15.18 litres. Hardly plausible, at least not the 15+ litres.
 
Also, the fuel gauge seems to differ in its accuracy, with owners observing anything from 7.8 to 10.5 litres going in when the F starts flashing.
 
Maybe it is possible to fit a resistor in order to get the gauge to indicate more accurately?
 
________
My personal theory is that the computer will shut down the engine before the tank is bone dry to protect the cat. And that the bike first will warn the rider by missing, like it's running out of fuel. Now, since the gauge isn't spot on, I reckon you can run "dry" anywhere between 13 and 14 litres. Maybe sooner.
 
If you want to know exactly how much your fuel tank will take when it runs dry, bring a gallon / 5-litre can along and ride until the bike stops. Make sure you are in an area where gas stations are close by. Fill up with the content of your can, reset trip and ride to the nearest station. Fill to the brim, add the amount from the can and subtract the amount you used to get to the gas station.
 
Or simply expect 13 effective litres and act accordingly

[rick]

It's hard on fuel pumps to run them dry, so I won't be doin that experiment. Be that as it may, it is what it is. Had there just been a warning light instead of a gauge, My math would still come up short of yamaha's

[faffi]

AFAIK, all cars today will shut down before you actually run empty, and I would expect current bikes doing the same. Both to protec the fuel pump and, more importantly, to protect the catalytic converter from burning up.

[rick]

don't know with cars - it would make sense to have those protections. But a lot of bikes will just run until they are dry.

[faffi]

Seems you are correct, Rick:
 
"So, after a little bit of background, back to the reader’s question. Your fuel-injected bike is about to run out of gas. Your pump starts to cavitate and then runs dry when fuel is no longer present, the bike quickly stalls as the injectors have nothing to spray and you would turn off the ignition. Every F.I bike I have had experience with has a fuel pump shut off system built into the ECU to keep the pump from working while the ignition is turned on but the engine is not running. This same system is what you hear prime, then shut off the pump after you turn on the key but before you start your bike. If you do run the tank out of fuel (as we do on the race team all the time to measure fuel remaining after practice sessions), just cycle the key switch a couple of times to re prime the system. If the area is quiet, you will hear the air purge back into the tank from the fuel rail and the pump load a little as it re primes. I have run a number of fuel injected bikes out of fuel on the dyno, both on purpose and while hoping to do 'just one more run' with zero side effects. The odd time you will hear of an old snowmobiler (usually) that claimed to have seized an engine while running out of gas. The design of the float bowl in a carburetor would allow you to ‘dry up’ the pilot jet for an instant before running the main jet out fuel, stalling the engine. For this to be the cause of seizing an engine, you would have to be riding a carbureted two stroke, on the ragged edge of detonation already, with EGT’s through the roof for that brief moment of a lean condition to be the reason for an engine failure. Chances are, the engine was on it’s last tank of fuel anyway, you just had a different excuse to blame the seizure on. So go ahead, run that tank as low as you dare, just have a buddy around with a siphon hose… eh Mark?"
 
From: http://www.acceltechracing.com/tech/Running%20a%20bike%20dry%20of%20fuel.htm

[bugeyes]

I picked up a 2017 FZ-07 on April 15/ The fuel gauge thing was the first i noticed. Something to get used to i guess. When i saw the last bar i stopped to fill up. Tank was just under half full. Only put in approx 8liters (of 14).
 
I guess the main thing to get used to is how far to trust the F range indicator. If the bars indicator is not accurate,
how far do we trust the xx liters to empty F gauge?

Same for me but I'm not concerned about it and just fill up at the last bar, never got more than 9 liters in it