Very thirsty f700gs

[soupdragon]

I've had my 2012 f700gs for a few weeks now and am a bit disappointed with its fuel consumption. After reading about some members on here achieving over 200 miles before re-fueling I was surprised to see the warning light come on after 100 miles. When I filled up after 140 miles it took 15.25 litres! That's 42 mpg. I ride very gently, mostly under 4000 rpm. It's done 20k miles, full BMW service up to 18K. Newish chain, correct tyre pressures. It does have a Givi Airflow screen, Givi 55 litre topbox and large soft panniers fitted.
Does anyone else get poor economy from theirs and what would be the causes? It has a Scotoiler fitted - has that upset the throttle vacuums? Do these plastic petrol tanks leak? I'm sure that if I really caned it I could get down to 35mpg - thats 2-stroke and large 4 cylinder sports bike territory!

 

[alex_rsa]

I've had my 2012 f700gs for a few weeks now and am a bit disappointed with its fuel consumption. After reading about some members on here achieving over 200 miles before re-fueling I was surprised to see the warning light come on after 100 miles. When I filled up after 140 miles it took 15.25 litres! That's 42 mpg. I ride very gently, mostly under 4000 rpm. It's done 20k miles, full BMW service up to 18K. Newish chain, correct tyre pressures. It does have a Givi Airflow screen, Givi 55 litre topbox and large soft panniers fitted.
Does anyone else get poor economy from theirs and what would be the causes? It has a Scotoiler fitted - has that upset the throttle vacuums? Do these plastic petrol tanks leak? I'm sure that if I really caned it I could get down to 35mpg - thats 2-stroke and large 4 cylinder sports bike territory!

Check if the plugs are sooty...my fuel range plummeted from 200 miles to 140 miles overnight. After months of trying to find the problem it was the fuel pressure sensor giving a low reading. This caused chronic over-fuelling.

Sooty plugs and black smoke form the exhaust were the tell tales.

If you have access to a GS911 you want about 4bar fuel pressure.


...then again it may be the scott-oiler...

 

[Ash]

2011 650 15K miles, never thrashed, usually keep more or less to speed limits and mine never drops below 60 MPG & usually sits around 62 - 63 MPG

 

[kyojitsu]

That's unusually low I would say. Also check to see if your brakes are binding - possibly the rear. My 800GS responds much better to super plus inleaded. I have no idea why it just does - might be worth a tank or two for comparison. However even with me riding briskly along country B roads and not being particularly careful I get 52 mpg on average. I still thank that's a bit low mind you so will be interested in finding out what's going on with your bike.

 

[Chicken]

Might Help

This screen dump from my iPhone app might help

 

[patzx12]

Double check the air filter, is it clean?

 

[soupdragon]

I've stripped and cleaned all 3 brakes - they weren't binding. Checked the vacuum pipes to Scotoiler. It's got be engine management problem - some sensor is sending false information, I would think.

 

[alex_rsa]

I've stripped and cleaned all 3 brakes - they weren't binding. Checked the vacuum pipes to Scotoiler. It's got be engine management problem - some sensor is sending false information, I would think.

You are on the wrong forum to get much technical information, ADVRIDER has a much more active 800 forum. It took me 3 months to work out why my bike was overfuelling and I have a GS911.

Your easiest approach would be to get a GS911, if you post a reading of all the current settings I can check against mine. My fuel pressure was reading 2bar which caused the fuel pump to run all the time trying to get the pressure up to 4 bar.

It may be something else like a duff Lambda sensor but they are supposed to be very robust and also they only start affecting the fuel when they are at 70c.

Does you bike run rough when blipping the throttle? What you can try is to unplug the fuel pressure sensor (it's on the end of the fuel rail) and see if it runs better. Unplugging the sensor causes the management to go into fail-safe mode and show 6bar fuel pressure.


Cheers

Alex

 

[kyojitsu]

alex - how bad was your fuel economy? What symptoms got you looking at overfuelling as a problem? I have a hunch my bike isn't quite running as it should although it's not REALLY sick. I don't really want to shell out £300 for a GS911 but don't want a day wasted going to the dealer.

 

[alex_rsa]

alex - how bad was your fuel economy? What symptoms got you looking at overfuelling as a problem? I have a hunch my bike isn't quite running as it should although it's not REALLY sick. I don't really want to shell out £300 for a GS911 but don't want a day wasted going to the dealer.

1. Fuel consumption dropped from 200 to 140 miles per tank overnight
2. Lots of crackling and banging form the exhaust on overrun
3. Visible (but light) black smoke when blipping the throttle and poor response
4. Lumpy idle
5. Both spark plugs black and sooty

If you have the above symptons then I would try unplugging the fuel pressure regulator and see if the idle and the response to blipping the throttle improves. It is accesible if you remove the right-hand side cover.

You could try a request on the 1200 forum for anyone with a GS911 near you.


Here is my thread form ADVRIDER http://advrider.com/index.php?threads/gs800-rough-running-and-30-decrease-in-mpg.1095417/ there is also a more comprehensive one started by someone doing an overland trip. Someone advised what sensors could be unplugged and what should happen. That is what prompted me to unplug the FPR

Good luck

 

[kyojitsu]

Thanks for the info. Very interesting. I'll investigate further.