Extremely low MPG

[BigBlueF1]

Hi all, me again.

Today I was riding and noticed I only went 5 miles before one of the bars dissapeared on the gas gauge. Theres only 10 bars I believe. If Im only getting 5 miles per bar than that means Im only getting 8-10 miles per gallon? Only 60 miles on a full tank around town vs others getting 300. I know I got a little over 100 on a full tank on the highway as I rode it 300 plus miles when I bought it. I had to fill up around the 110 mile mark as it was getting low.

I just bought the bike and everything seemed good on it and the owner seemed honest and took good care of the bike. Im worried now. One of the reasons for getting the bike was that its good on gas.

Is it possoble the Power Commander is causing me to get terrible gas mileage? I am tapped out of money right now so I cant take it into a mechanic otherwise I would.

Anyone ever seen this?

 

[Ignacio]

Something doesn't add up here. But I can't tell if it's your funky and suspect way of sorta estimating mileage, doing gymkhana stuff in town, or actual issue with the bike.

First, don't obsess on fuel indicator segments. Once you have a full tank of fuel how many miles do you travel on that tank according to the odometer or trip meter AND how many gallons does the fuel pump say to fill up to that same spot in the tank? That's the proper way to estimate actual fuel mileage.

 

[RiderJoe]

@BigBlueF1 , your fuel gauge is nothing more than a guesstimator. Not a precision instrument. I have an ‘06 too, and mine works the same way as yours. It matters how full your tank is after filling. I find that if I fill the bike on a center stand, and at a lower flow rate towards the top, the first bar stays lit much longer (= fuller tank). You should get mid 40 mpg with conservative throttle use. I have a PCIII installed too. I usually get gas around 220 miles of riding, and at that point I fill about 5 gallons of gas, with the last bar about to start flashing. The tank holds 6.6 gallons.

 

[Whooshka]

Did you actually look in the tank or fill up to see how much was in there? It could be just a bad sending unit.

 

[BigBlueF1]

Something doesn't add up here. But I can't tell if it's your funky and suspect way of sorta estimating mileage, doing gymkhana stuff in town, or actual issue with the bike.

First, don't obsess on fuel indicator segments. Once you have a full tank of fuel how many miles do you travel on that tank according to the odometer or trip meter AND how many gallons does the fuel pump say to fill up to that same spot in the tank? That's the proper way to estimate actual fuel mileage.

Haha, I filled up the tank to full last night only about 2 miles or so from home. I went to school today and back and thats it and lost 2 bars.

I try to take it easy on the bike. I dont go very fast or rev it very high and I was trying to stay in 2nd or 3rd most the time. 3rd if I had a little longer of a stretch.

I will have to try an keep an eye on my mileage. Thank you for your reply. Makes me feel a little better. Im gonna keep watching it.

 

[BigBlueF1]

@BigBlueF1 , your fuel gauge is nothing more than a guesstimator. Not a precision instrument. I have an ‘06 too, and mine works the same way as yours. It matters how full your tank is after filling. I find that if I fill the bike on a center stand, and at a lower flow rate towards the top, the first bar stays lit much longer (= fuller tank). You should get mid 40 mpg with conservative throttle use. I have a PCIII installed too. I usually get gas around 220 miles of riding, and at that point I fill about 5 gallons of gas, with the last bar about to start flashing. The tank holds 6.6 gallons.

Interesting about putting it on the center stand. Id be surprised if Im getting 40. Even 30. Im being easy on the throttle. Im not riding it hard by any means.

If you are getting 220 then your still only getting 30 mpg right? Do you think of you took the power commander out that it would get better gas mileage? Does the power commander help at all do you think? Im glad that someone else on here has the same year and even equipment! Thank you!

 

[BigBlueF1]

Did you actually look in the tank or fill up to see how much was in there? It could be just a bad sending unit.

I havent really looked in it really well when it got to the point of blinking. Just a glance. Ill keep an eye out next time I fill up and check the mileage. Im taking it easy on the bike so its kind of disheartening if it is.

Thanks for replying

 

[RossKean]

The fuel gauge is notoriously non-linear. The first segment and the last segment (before it starts flashing) tend to disappear quickly. I assume yours is a Gen II since you are using a Power Commander?

That said, around town, short hops and stop-and-go riding will net you terrible fuel mileage. 25 mpg or less, depending on circumstances. (NOBODY gets 300 miles per tank under those conditions!)

The principle advantage of a Power Commander on FJRs is to reduce throttle abruptness by making the mixture richer at low throttle openings. I had a Power Commander on my 2007. I ended out removing it because it made a significant difference in fuel usage. Throttle was more snatchy but I got used to it. Little or no point in a Power Commander for any FJR 2009 or later, IMHO. It won't net you any more HP and Yamaha had improved the stock ECU mapping by that point.

 

[Ignacio]

If you are getting 220 then your still only getting 30 mpg right?

It depends. As I said before, how many gallons did you actually use to go those 220 miles? To get 30 mpg and 220 miles you'd need to put in 7.3 gallons and that wouldn't be possible as the tank only hold 6.6 gallons. If, for example, you put in 6.0 gallons as a far more common scenario for most of us--you'd get be getting 37 mpg.

Distance traveled / gallons used = MPG

 

[RiderJoe]

If you are getting 220 then your still only getting 30 mpg right? Do you think of you took the power commander out that it would get better gas mileage? Does the power commander help at all do you think? Im glad that someone else on here has the same year and even equipment! Thank you!

With 220 miles ridden on about 5 gallons of gas, it would be around 45 miles per gallon, no? OK, my bad - 44 mpg. . I bought the bike with the PCIII on it already, so I don't know what it would be like without it. My previous bike, the '03, had a different acceleration feel. I am on a fence about keeping the PCIII. Maybe one day I will take it off, and try Ivan's flash.

Most of my riding is in traffic-free, hilly roads, so I think that my mileage only dipped below 40 once or twice. On the other hand, I also got above 50 once or twice - on a mostly declining path.

 

[roger dodger]

BBF1, I think you may be thinking too much about the bars. Ignore the first half of the tank. It's not accurate.

Also, my first goal in buying a used bike would be to check out all the systems for maintenance, and remove extras that you don't need. Start by removing the PC111 and go back to stock. Eventually you could add Ivan's Flash for $350 or so.

The saying goes ... 'Ride more ... worry less'. I suggest a full tank day ride of 200-300 miles and you and the bike can gel a little more. Watch for the miles after hitting 'reserve' and you may see 50 miles, and fill it with 5.5 gallons or so. I usually get 44 -45 mpg and still worry a little on reserve, so RIDE MORE.

 

[infrared]

BigBlue,

https://www.fjrforum.com/threads/proud-new-owner-of-an-fjr.179450/post-1448801

https://www.fjrforum.com/threads/proud-new-owner-of-an-fjr.179450/post-1448802

 

[torch]

The fuel gauge is notoriously non-linear.

Actually, I think the gauge -- or more precisely, the sensor -- is fairly linear, but it's a height gauge. It's the tank shape that is non-linear and Yamaha made no effort to correlate height to volume.

That pretty domed top just doesn't hold much gas. Drop a few centimeters and the tank both widens and lengthens before sharply narrowing again.

At a steady 105 to 110 kph (~70 mph) and fairly gentle hills, Legacy loses the first bar (of 16) at about 20kms (13miles) and the second bar at around 70kms (44mi). There's one bar left at about 325kms (200mi) and takes about 17L (4.5USG) to top her off.

Pandora's 8 segment gauge is actually more useful, if less precise. Under similar conditions the first bar lasted roughly 65kms, the next disappeared at perhaps 120. The remaining intervals were fairly consistent, approximately 45-50km each excepting the last- from the moment the 7th bar disappeared to the moment the fuel trip meter activated was generally only 25kms. At that point, she would need just under 20L to fill, leaving a 5L reserve capacity.

 

[MotoMike]

"Under similar conditions the first bar lasted roughly 65kms, the next disappeared at perhaps 120. The remaining intervals were fairly consistent, approximately 45-50km each excepting the last- from the moment the 7th bar disappeared to the moment the fuel trip meter activated was generally only 25kms. At that point, she would need just under 20L to fill, leaving a 5L reserve capacity."

This has been my experience with my 2007. Worry less-ride more!

 

[RossKean]

Actually, I think the gauge -- or more precisely, the sensor -- is fairly linear, but it's a height gauge

I consider the gauge is what you read so it is non-linear whether the sensor is or not due to tank shape. I am not sure if Yamaha made any attempt to linearize it or not. Except for the first and last, they seem to be similar although the tank is much wider in the top half (except the slope at the very top). The first segment depends on how much gas you squeeze in when you fill but still smaller than the rest.

Here is a (bad) photo of the resistor board from the stock fuel gauge. This might be a Gen I based upon the number of distinct resistor "patches" but you get the idea. The silver lines are where the wiper on the float makes contact and the black patches are resistive material. Judging from the varying shape/size of the eight patches, I would guess this is Yamaha's way of linearizing the output...



Reserve, on my bike, is something a bit over 5 litres. I have gone as much as 120 kilometers (75 miles) on it.

To the original poster, remember that the FJR has both an instantaneous and a "since last reset" mpg meter. Sometimes useful to see how riding habits (and terrain) affect fuel economy. Remember to reset when you fill, otherwise the "since last reset" gauge won't provide meaningful data. (It isn't really "since last reset" but more the last xxx miles (maybe 300 or so) - older data gets dropped out of the calculation.) A word of caution about the MPG meter - it is NOT accurate with a Power Commander. It is based upon how much fuel the ECU has told the injectors to provide and the PC re-interprets that and (usually) sends more to richen the mixture. The MPG meter is surprisingly close to calculated for my 2011.

I find the Yamaha gauge to be very accurate and reproducible compared to many other bikes. It does, however, go into count-up mode early if the bike has been on the sidestand. On my (recently acquired) 2017 BMW F700GS, the fuel gauge is little more than a suggestion. For the first approximate half tank, it just reports > (greater than) half. For the remainder, it gives you some sort of gauge with bars before a light comes on and it goes to count up. On my first fill, I put 16.2 litres into a tank that is only supposed to hold 16 litres of "useable" fuel!! This first fill was just a couple of days ago and in the future, I'll rely more on the trip odometer along with the MPG meter - still have to find out how accurate that one is. BMW says this is due to the oddly shaped fuel tank that resides under the seat. Imagine trying to design an accurate and linear fuel gauge for this...

 

[Mcarver351]

Next time you fuel your bike, top it off. Ride your bike the way you normally ride for 100 miles. Top it off again and record the the amount of fuel you put in the tank. Divide 100 by the gallons and that will be your accurate mileage. If the fuel gauge is showing empty and you only put 3 gallons in, you might have a bad sending unit. I have found my bike sips fuel on the open highway at cruising speed but guzzle it around town. I'm sure everyone on here knows why that is and that's the fun of riding a motorcycle. So many people buy a motorcycle thinking it is more economical than a car but those of us who have owned them all our lives knows that is not accurate, especially if you can't do your own maintenance. That is just what we use to tell our wives to justify our purchase.

 

[art miller]

That is a good summation of the topic!!

 

[sullivan]

With 220 miles ridden on about 5 gallons of gas, it would be around 45 miles per gallon, no? OK, my bad - 44 mpg. . I bought the bike with the PCIII on it already, so I don't know what it would be like without it. My previous bike, the '03, had a different acceleration feel. I am on a fence about keeping the PCIII. Maybe one day I will take it off, and try Ivan's flash.

Most of my riding is in traffic-free, hilly roads, so I think that my mileage only dipped below 40 once or twice. On the other hand, I also got above 50 once or twice - on a mostly declining path.

44 is fine. 47 is a better day. Hit 50 going to CFR, once.

 

[thefix]

To determine true mileage - always use center stand and truly FILL it up. I can easily fit another 1/2 gallon past the 1st PUMP click off. Back roads 250 miles in nothing. I have hit 250+ and still had a gallon+ in the tank. I follow a few guys who keep me from going at a lawly sane pace. I live in an extremely hilly area of 9% grades. You need to be sure your mileage sucks. I dislike power commanders and such, especially on FJR 2nd gen on...they can cause issues. Check your air filter that the mice haven't moved in. If not -Maybe remove the pwr commander

 

[RossKean]

To determine true mileage - always use center stand and truly FILL it up. I can easily fit another 1/2 gallon past the 1st PUMP click off. Back roads 250 miles in nothing. I have hit 250+ and still had a gallon+ in the tank. I follow a few guys who keep me from going at a lawly sane pace. I live in an extremely hilly area of 9% grades. You need to be sure your mileage sucks. I dislike power commanders and such, especially on FJR 2nd gen on...they can cause issues. Check your air filter that the mice haven't moved in. If not -Maybe remove the pwr commander

Early Gen II benefited from the Power Commander to tame a very abrupt throttle response. 2006 and 2007, in particular. Some people found the stock setup almost unrideable. Personally. I removed the PC and got used to it. I figured the device cost me 10 to 15% in fuel economy. A G2 throttle tube also helped some - it has a different ramp making for less movement at the lower end.

Now, a better solution for lean fuelling is an "Ivan flash" of the ECU. It will remove the throttle snatch and might even improve mileage over stock.
Edit to add link...

Ivan's Gen II Flash