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Offline Marcos1979

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High Fuel consumption - 100 miles with per tank :(
« on: 18 February, 2020, 03:36:23 PM »
Hi all, my bike MkI is now giving a very little milage per tank, I recall getting at least 150 miles in the city and 200 max on the motorway, would anyone have a clue of what the heck is going on? Thank you, Marcos.

Offline Art

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #1 on: 18 February, 2020, 04:37:34 PM »
There are many things than could cause poor fuel economy from the obvious fuel leaks, theft of fuel, binding of brakes, wheel bearings or transmission etc to a fuelling or ignition system fault such as air intake leak, coolant sensor, oxygen sensor, fuel injectors, poor compression. The list is almost endless and probably impossible to determine without a hands on diagnosis.

If its nothing obvious you need to get it into a garage. Have to hand details of anything that has been done between good and poor fuel economy together with details of when and what was done at the last service.

Offline Marcos1979

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #2 on: 18 February, 2020, 07:07:42 PM »
Hi Buddy, thanks a lot for your input, your time is appreciated. I take this to my mechanic and ask him to go through this, definitely It is a concert as the bike doesn't even has 30k on the clock.  Fuel theft or leakage is out of question but I will send your email across to him to start the troubleshooting. Have a great evening buddy.

Offline NJD

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #3 on: 19 February, 2020, 11:01:18 AM »
I don't really see the problem, but would be interesting to see what your MPG is?

Your commuting in London on a 1000cc. I'd be surprised if you ever needed to go above 3rd (on the inner city). I don't know what more your expecting.

For running performance you could look at the condition of the air filter or if you want an idea of how the engine is running the spark plugs.

I get about 90-100 miles for 10-11 liters worth of fuel, and at that point the tank is full (and at those 90-100 miles the gauge is starting to edge near the start of the red [reserve] area on the gauge). That's all city based on, at most, 40 mph roads.

Also worth keeping in mind that it is winter. Fuel injection increasing fuel load to get the bike up to temp (much in the same way you'd adjust idle speed on a carb over the cold months)?

Offline Marcos1979

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #4 on: 19 February, 2020, 12:30:28 PM »
Hi NJD, thanks a lot for your reply, your time is appreciated.

I have just changed the spark plugs as the filter is new. Now, if you are saying that you do 100 miles with 10 litres and the fuel gauge is going to red, you still have 9 liters left...? What happened to the 9 Liters, before I used to do at least 140 miles with a full tank, now I barely do 100 :(. Any other thoughts, thanks youfor your time buddy.

Offline NJD

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #5 on: 20 February, 2020, 04:03:54 PM »
Interesting, never really played too much attention to that. Hiding in the bottom of the tank, possibly. I fill up on the sidestand until the nozzle stops itself, but it does always look empty (the bits I can see) when I open it up.

With the reserve being part of the main tank (no fuel tap) I dare not to end up pushing the thing for fear of sleeping on the roadside under the engine.  :008:

May try and push it for one more commute than usual each time and see what happens. I know gauges are not accurate but 9 litres out is quite extreme (is that common on this model?).

Impending workshop post when I'm tired, try to start it and can't figure out why it wont fire.  :mfrlol:

Lets us know you get on at the shop.

Offline Art

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #6 on: 20 February, 2020, 05:11:17 PM »
Calculations in the traditional miles per gallon for the UK please. Litres per 100 kilometers or miles per liter if you prefer but something more tangible than miles per tank because per tank varies too wildly.

Combined urban + extra urban mpg should be something in the order of 50+ mpg, that translates to 11 mpl or, 9 litres per 100 miles. Which also gives around 200+ miles per 19L tank full but you'd need to the bar when fuelling up and then run it virtually dry to realise that. Reduce theses figures by around 15% (42 mpg) if all your riding is urban city driving, increase the figures by 15% (58 mpg) if all your riding is extra urban B-roads, A-roads and motorways.


Offline Marcos1979

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #7 on: 23 February, 2020, 03:59:35 PM »
Hi all, we have checked everything, biding breaks, O2 sensor and the list goes on... the only issue we have found is that the breaks were binding a little bit but not much so now Ihave fulled the tank with STP injection cleaner and now waiting to see whether I will get more mileage. I will keep you updated.

I am also wondering if there is an issue with the fuel gauge. I am considering riding until I run-out of fuel to see whether the issue is with the gauge.

I will keep you all posted and thank you for your support.

Cheers,Marcos.

Offline Art

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #8 on: 24 February, 2020, 12:56:33 AM »
No need to run out of fuel. If you look inside the petrol tank you'll see a bar just below the filler hole. With the bike on its side stand fill the tank to that bar, ride for 100 miles and with the bike on the side stand fill the tank to the bar again. If it takes 9 litres or less that is 50+ mpg and about right. Repeat the above exercise but ride it 150 miles and expect it to take 13.5 litres or less.

If you're feeling really adventurous you could try for 200 miles and expect to re-fill with 18 litres but note at 50 mpg you're only leaving 1 litre of fuel and 11 miles in the tank.

I regularly ride mine 180 miles with a 16 litre refill, got to 210 miles for 18 litres once.

Offline Marcos1979

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Re: High Fuel consumption - 100 miles with per tank :(
« Reply #9 on: 24 February, 2020, 06:25:09 AM »
Hi Art, thanks for that, I will try and will let you know :) Have a nice week ahead buddy. Marcos.