Low MPG reading?

Joined
Sep 24, 2017
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uk
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2004 Honda ST1300
2004 ST1300 10,000 MILES

Hi there I am new here and not sure where to post but here it goes.

I have a 2004 ST1300
The air filter is clean, The plugs are good and the oil and oil filter are good.

It starts, idles and runs perfect but the current MPG reading says anything
from 6MPG 8MPG 10MPG and the best I've got in 5th gear at low revs is 14MPG

Any ideas or help would be really appreciated, thank you, its a lovely bike and I
just want it to be right.
 
Joined
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Cleveland
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Re: CAN ANYONE HELP ME PLEASE.

If it runs with no problems (other than the mpg reading), I'd fill up the tank, take it for a 20 to 40 mile ride and fill up again at the same gas pump. Then calculate mpg. This will tell you if your computer is misreading or if something is very wrong. Oh, and since the odo works by impulses off the engine, when you hit the interstate, zero the trip meter at a mile marker, ride your 10 miles and see what the trip odo says.
 
Joined
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Wisconsin
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2006 Honda st1300
Re: CAN ANYONE HELP ME PLEASE.

Brakes could be dragging. Put bike on center stand, put in neutral and spin the tire. You should get about 1 revolution. If not, the brake is dragging some. But for your low mileage, it would have to be dragging to where you can't turn at all. Mine dropped 10mpg when the rear brake was dragging. But low mileage like yours is probably a combination of issues. Dirty injectors could be the culprit also. The st1300 should get 40mpg overall. I currently get 41.
 
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DavidR8

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Hi Daryl,
I'll chime in as I recently experienced low fuel mileage as well.
I would ignore the dash display and do a motorway ride. Fill up at the start, zero out your trip meter and ride at least 60-100 miles.
Return to the same filling station and fill to the same level.
Work out your mileage from those numbers.
The odometer is optimistic by about 8-10% but it's accurate enough to figure out if you have a significant issue.
I did this recently and discovered that I got just over 48 US mpg whereas previous city riding in lots of stop and go traffic had me running at about 22 US mpg.

Prior to this I had a rough idle problem which was fixed by cleaning the 5-way T which is located under the air box.

You can read my saga here: Is this normal gas mileage?

https://r.tapatalk.com/shareLink?share_fid=913&share_tid=160579&url=http://www.st-owners.com/forums/showthread.php?t=160579&share_type=t


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DavidR8

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Re: CAN ANYONE HELP ME PLEASE.

If it runs with no problems (other than the mpg reading), I'd fill up the tank, take it for a 20 to 40 mile ride and fill up again at the same gas pump. Then calculate mpg. This will tell you if your computer is misreading or if something is very wrong. Oh, and since the odo works by impulses off the engine, when you hit the interstate, zero the trip meter at a mile marker, ride your 10 miles and see what the trip odo says.
The odometer works off impulses from the engine?
How does that work?
(Curious not questioning [emoji846])


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Joined
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Kendall Park, NJ
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Re: CAN ANYONE HELP ME PLEASE.

There are two MPG modes when you are looking a the meter, one is "Current Fuel Consumption" and the other is the "Average Fuel Consumption" Current Fuel Consumption fluctuates a lot. You can cycle the modes by pressing the "FCD/H" button.

I would also reset the trip meter, fill the tank, record fuel used at the next fillup and calculate it manually. I have found the meter reads low MPG for me.

Regards,

Keith

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Blrfl

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Re: CAN ANYONE HELP ME PLEASE.

The odometer works off impulses from the engine?
How does that work?
The odometer is driven by pulses from the vehicle speed sensor, which also drives the speedometer.

--Mark
 
Joined
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Grand Rapids, Mn
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I never use the "instant" fuel mileage reading, but I run the tank "average" display. At the end of each tank after refueling to the same "to the rim" level while on the centerstand method I calculate my mileage and write it all down in a log book. The display tank average for me is consistant in being about 3 mpg lower than "actual". (I say "actual" because I don't do any corrections for odometer error).
My season average has been 49 mpg. Recent touring trip loaded with passenger and gear was 50.5 mpg.
Good consistant records help diagnos issues rather than guessing about them.
 

Andrew Shadow

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Over a total of 63, 076 KM (39, 194 miles) since new my average is 55.8 miles per imperial gallon- 47.6 miles per US gallon. This is 19.7 Km/L which is exactly what may on-board fuel computer average display always reads as well. This is based on the odometer- i.e. does not include any compensation for odometer error.
 
OP
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Hi there and thank you for your input. I filled up the tank to the very top and rode 128 miles and my fuel
gauge was on 1 bar and flashing, then it changed to 18 miles and went down very fast.
 
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The displayed number is mpg only when 2 or more bars of fuel level are displayed. When only 1 bar is present the number displayed is the calculated distance to empty.
 
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128 miles on 6 gal. Would be consistent with and 18 miles to empty reading on the display. There was a problem with the 2204 bikes that the thermostat got stuck open, causing the engine to run cold. This would be indicated by the temp display showing only 2 bars, rather then 3. This was a mfg problem that too much release compound was used in the mfg of the radiator hoses. The compound flaked off the inside od the hoses collecting on the thermostat, jaming it open. A cold running engine may only get the mpg you are seeing.
 
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I have a 2004 with this problem. Replaced the thermostat and radiator hoses, and extensive flushing of engine, radiator and over flow bottle. Then, a couple months later the water pump started leaking.
 
Joined
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Hi there and thank you for your input. I filled up the tank to the very top and rode 128 miles and my fuel
gauge was on 1 bar and flashing, then it changed to 18 miles and went down very fast.
I think you have a fuel leak issue more than a consumption issue.
Go refill it and see how much fuel you actually used.
 

DavidR8

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So that we're clear:
You filled up and rode 128 miles and your guage was reading one bar remaining.
Don't rely on the gauge for level or distance remaining.
Did you fill up again to see how much you actually used?

If you used virtually all of the 8 gallons available in 128 miles I agree with Jettawreck; you have a fuel leak.
 
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STumped

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Hi there and thank you for your input. I filled up the tank to the very top and rode 128 miles and my fuel
gauge was on 1 bar and flashing, then it changed to 18 miles and went down very fast.
That is terrible gas mileage (21.3)! What is the weather like there in the UK? I ask because if it is on the cool side (or cold) you may have a stuck thermostat. Does your temp gauge read three bars? It should. If not, the engine is not reaching proper operating temperature and the ECU is enriching the fuel mixture and wasting gas. You should probably check that your brakes aren't dragging as others have suggested (the rear, especially).

Good luck and let us know what you find.
 
OP
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Hi there friends, ok the weather here is quite warm at the moment, my temp bar reads 3 bars,
I'm going to do as you said, fill it up right to the top and run it down then I will go and refill
again and do some math.

if it was leaking petrol where and when would it leak from as there is no sign of petrol leak
when parked over night on my drive and I can't smell any petrol?. once again thank you all for your time.
 
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Just for a comparison...

I have a new-to-me 2004 ST1300 with 74000 miles and 2-brothers aftermarket exhaust. Just did 284.6 miles on 7.2 gallons for 39.5 miles/gallon.
I have not calibrated the odometer/speedometer against some mile markers but that's a good thought. I'll have to do that sometime.

My fuel gauge started flashing one bar at about 244 miles so I did another 40 miles with it flashing and still had a half gallon (~20 miles) left when I stopped for fuel. Seems that 50 miles while flashing is comfortable.

I was hauling 180lb of person and about 120lb of tree working gear during this run. Combined highway/city driving.

Later,
Kent Larson in Minnesota
 

DavidR8

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Hi there friends, ok the weather here is quite warm at the moment, my temp bar reads 3 bars,
I'm going to do as you said, fill it up right to the top and run it down then I will go and refill
again and do some math.

if it was leaking petrol where and when would it leak from as there is no sign of petrol leak
when parked over night on my drive and I can't smell any petrol?. once again thank you all for your time.
If you can't smell gas then maybe it's not a leak. To get that kind of low mileage I'd think one could smell gas.
I'm really curious about your actual consumption when you fill.


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STumped

Because I usually am . . . .
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Just did 284.6 miles on 7.2 gallons for 39.5 miles/gallon.
I have not calibrated the odometer/speedometer against some mile markers but that's a good thought. I'll have to do that sometime.

My fuel gauge started flashing one bar at about 244 miles so I did another 40 miles with it flashing and still had a half gallon (~20 miles) left when I stopped for fuel. Seems that 50 miles while flashing is comfortable.
Hooooweeee, Kent. You were on FUMES. I say that because I also have a 2004 and have run out of gas and actually coasted into a gas station. I put her on the center stand and filled to the top and all I could fit in there was 7.4 gallons. I know the manual says the fuel capacity is 7.7 gallons but I (and others) have only been able to fit 7.4 in a dry tank so it would seem that .3 gallons is unusable. At 39.5 mpg, you had 7.9 miles left until empty! Talk about cutting it close. ;)
 
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