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[Chuck Pryor]

I typically keep my speedo trip gauge set to miles "remaining" all the time... just a quick easy way to see how far I can go before I need to fill up. Over the past few month's I've noticed a HUGE discrepancy in the # of miles "remain" right after a fill up.  On the most recent road trip I took it would be 225 miles on one fill up. The very NEXT fill up it would be 178 miles. Next one would be 190 miles... all in the same day, similar weather, terrain, etc. I always top it off the same... always use highest octane from Shell/Chevron, etc but it always seems inconsistant. Engine has Andrews 54 cams, X-Pipe, Master Tuner, etc.

Anyone else experience this??

Chuck

[Twolanerider]

Differences in octane nor anything in the engine would have any effect on this.  Just a function of where the float is in the tank and the accuracy of the fuel level sending unit.  A difference in how full you get the tank will make a difference.

No one ever said much on a Harley was consistent.  I'd just be glad the tank held gas without leaking....

[Chuck Pryor]

I could see maybe 225, 220, 215, 210, etc...   but 225 to 178 back to back?  And from 40MPG to 32 MPG from one tank to another? Does not seem to be any pattern other than just very inconsistant.  I'm very careful about topping off at the same spot every time... 

[spydglide]

Differences in octane nor anything in the engine would have any effect on this.  Just a function of where the float is in the tank and the accuracy of the fuel level sending unit.  A difference in how full you get the tank will make a difference.

No one ever said much on a Harley was consistent.  I'd just be glad the tank held gas without leaking....

That's so old school.  You've got to get in the new modern approach to these machines....expecting all the bells & whistles to function as intended.  Hold gas    har!  spyder

[Twolanerider]

I could see maybe 225, 220, 215, 210, etc...   but 225 to 178 back to back?  And from 40MPG to 32 MPG from one tank to another? Does not seem to be any pattern other than just very inconsistant.  I'm very careful about topping off at the same spot every time... 

Are you saying you're actually getting that variation in fuel usage (from 40 to 32) from one tank to another (hadn't mentioned that in your first post) as measured usage?  Or is that inferreed mileage based on the variation in distance to empty after a fill up?

If you're seeing such a significant difference in actual measured fuel usage from one tank to the next, and there's no major difference in how you were riding or the conditions you were in, than, yeah; that suggests a problem to be tracked down.  Still not something that stems from a difference in fuel octane though.  Octane is only an anti-knock measure.  So unless you also started hearing a lot of detonation the differences in your fuels weren't an issue.

This makes it more interesting though.  What other details can you think of?  Any other differences in how it runs? 

[Twolanerider]

That's so old school.  You've got to get in the new modern approach to these machines....expecting all the bells & whistles to function as intended.  Hold gas    har!  spyder

I can't say anything without being a hypocrite Spyder.  After all, I can't hold my gas without leaking... 

[Chuck Pryor]

Are you saying you're actually getting that variation in fuel usage (from 40 to 32) from one tank to another (hadn't mentioned that in your first post) as measured usage?  Or is that inferreed mileage based on the variation in distance to empty after a fill up?

If you're seeing such a significant difference in actual measured fuel usage from one tank to the next, and there's no major difference in how you were riding or the conditions you were in, than, yeah; that suggests a problem to be tracked down.  Still not something that stems from a difference in fuel octane though.  Octane is only an anti-knock measure.  So unless you also started hearing a lot of detonation the differences in your fuels weren't an issue.

This makes it more interesting though.  What other details can you think of?  Any other differences in how it runs? 

Does not seem to be any perceivable performance difference... I have been getting a big puff of smoke out of the intake about half of the time I try to start it up. And it makes a heck of a noise when it does that too...  but again, I can't seem to find any pattern to what/when/why it does it.

[Twolanerider]

Does not seem to be any perceivable performance difference... I have been getting a big puff of smoke out of the intake about half of the time I try to start it up. And it makes a heck of a noise when it does that too...  but again, I can't seem to find any pattern to what/when/why it does it.

Still not sure what you're suggesting on your fuel usage.  Are you inferring mileage based only on the distance to end measurement supplied by the bike as that measurement varies from tank to tank?  Or is that actual measured fuel usage that is varying?

[JCZ]

Chuck, I see you changed your user name.  CAP is easier to type.

The inconsistencies your seeing in your fuel gauge at fill ups seems to be consistent with Harley gas gauges and all there other gauges......read that "consistently inconsistent".

You could switch over to the Dakota Digitals but I'm afraid they don't make em in silver.

[Chuck Pryor]

Still not sure what you're suggesting on your fuel usage.  Are you inferring mileage based only on the distance to end measurement supplied by the bike as that measurement varies from tank to tank?  Or is that actual measured fuel usage that is varying?

Sorry Twolaner...  I've had this bike over two years and most of the time I've had it and would fill the tank I'd have about 220 miles "remaining" on the trip odo. I would typically get about 40MPG when i actually checked miles/gallons filled etc. For the past few month's I noticed it being in the 175-18- range when I went ot fill it up. So I checked the fuel mileage again... then I'm like at 32MPG. Again, similar riding style, weight, etc. Nothing too drastic in riding difference.  So then I fill it again... 220 miles in "remaining" when I start er up. I check the mileage and back about 40MPG.  Very next fill up (same day, about 190 miles later)  top it off as usual and the "remaining" says 178 miles. I check it again, and it's about 31MPG. So yes, in the same day (within just a few hours)  I can go from 40 MPG to 31 MPG with no unusual change in riding style, weather, etc. I always use highest octane fuel and no generic gas stations etc. The rear of the bike (it's silver) seems to have a lot of black "exhaust" gunk on it like it's running very rich too...    

[glens]

Since I don't know you, what you ride, or how you ride it, and the same goes for you, my input may not be pertinent at all or it may be perfectly so  

I just got a new '12 ("standard") Ultra mid-August.  Below are a couple columns from a spreadsheet.  'Total Tank' is a derived figure obtained by multiplying the MPG achieved during the just-replaced tankful by "6".  'Initial "r"' is the value that first popped up on the way from the pump to the street "this" time.

Naturally, in a perfect world, the "current" 'Initial "r"' would coincide with the "next" 'Total Tank', but it doesn't...

I haven't decided whether or how the decision is made to present the initial "r" value, but suspect it has a lot to do with the most recent fuel usage pattern ciphered into how full you just got the tank.  So if you're out blazing around and pull into the pump it'll likely be lower than if you'd just got done casually putting a full tank of highway cruise-control under your belt.

Changing levels of oxygenates in the fuel one tank to the next will be a large factor in the spread from one time to the next.  I don't believe I've used any oxygenated fuel in what follows, and in fact only two fill-ups were from a single different station than all the others.

Total Tank  Initial “r”
   222.5        211
   217.7        213
   229.4        228
   232.4        227
   248.2        245
   221.8        234
   249.7        241
   244.3        230
   235.6        231
   233.1        227
   238.8        244
   216.4        233
   252.5        251
   250.5        249
   238.9        246
   243.1        241
   239.6        248
   236.7        250
   256.1        247
   249.1        267
   242.4        254
   255.9        253

I've had this bike over two years ... and ... would typically get about 40MPG ... For the past few month's I noticed it ... go from 40 MPG to 31 MPG with no unusual change in riding style, weather, etc. ... The rear of the bike (it's silver) seems to have a lot of black "exhaust" gunk on it like it's running very rich too...

Could be your O2 sensor(s are) going "south".  They'll get weak and lazy and act like the engine's running lean.

[spydglide]

I know the ethanol-blends give less mpg than the 100% gasoline and also I've heard that there are seasonal-blends that may give different mileage.  Maybe you're getting the winter gas on some fill-ups and the summer blend on others?  That's quite a lot of variance for the same bike and rider if the conditions are about the same though.  Might be something else going on with the fuel mgt. system.  ??  Maybe some of the motor experts will chime in here and solve your puzzle.  spyder

[Twolanerider]

Sorry Twolaner...  I've had this bike over two years and most of the time I've had it and would fill the tank I'd have about 220 miles "remaining" on the trip odo. I would typically get about 40MPG when i actually checked miles/gallons filled etc. For the past few month's I noticed it being in the 175-18- range when I went ot fill it up. So I checked the fuel mileage again... then I'm like at 32MPG. Again, similar riding style, weight, etc. Nothing too drastic in riding difference.  So then I fill it again... 220 miles in "remaining" when I start er up. I check the mileage and back about 40MPG.  Very next fill up (same day, about 190 miles later)  top it off as usual and the "remaining" says 178 miles. I check it again, and it's about 31MPG. So yes, in the same day (within just a few hours)  I can go from 40 MPG to 31 MPG with no unusual change in riding style, weather, etc. I always use highest octane fuel and no generic gas stations etc. The rear of the bike (it's silver) seems to have a lot of black "exhaust" gunk on it like it's running very rich too...    

That's a variation worth paying some attention to.  Certainly suggests you've got something going on. 

If you're chasing the problem yourself I'm always a firm believer in checking the easiest and cheapest things first unless it's something patently obvious.  So check for intake or exhaust leaks.  Not necessarily the most likely.  But a leak in either place will effectively spoof the o2 sensors and things will wander a bit.  Have to wonder about an o2 sensor itself also.  They can fail gradually and in ways we'll not really feel while riding. 

Hopefully you'll not have to chase a problem through the bike's entire sensor suite or elsewhere and one of the more obvious or easy potential solutions will take care of it.  Will keep my finger crossed you get it knocked out without too much trouble.

[MKW]

Does the "fuel remaining" readout have anything to do with prior riding habits?  I noticed that when I completed 3 hours of highway riding and filled my tank it showed 220 miles remaining but when I am in traffic and have hard starts and plenty of shifting it seems to read lower after fill-ups.  I'll pay closer attention to it now.  I do know that when my actual fuel needle is on empty I can only put in 4.5-5.0 gallons or so but never over 5 and I have a six gallon tank.

[2018_FLTRXSE]

I notice I stay pretty consistent unless I'm banging on the bike HARD..

I go from 225 down to about 195 per tank... the commute is short and most times with little traffic. I've gotten as low as 170 but that was an extreme weekend of having lots of fun.