Overfuelling - fuel consumption increased by 30%

[alex_rsa]

What can cause overfuelling?

Bike is popping and farting on overrun, acceleration is medicore and will start misfiring if accelerating to hard. Lumpy idle.

Also fuel consumption has plummeted from 200 miles to 150 miles on a tank - I ran out!

Change the spark plugs this morning, both black and sooty. New plugs made no difference.

Sugestions? I have a GS911 that I will connect tonight.

Thanks

Alex

 

[karlp]

Air filter blocked
Coil packs

 

[Mav]

Air filter blocked
Coil packs

Sounds like the lambda/O2 sensor... at least those are the symptoms I had when they failed on my GS

 

[alex_rsa]

Thanks Mav,

Looks like a trip to BMW parts for a new sensor...

 

[v8legend]

Bike is popping and farting on overrun, acceleration is mediocre,
Also fuel consumption has plummeted from 200 miles to 150 miles on a tank.

Sugestions? I have a GS911 that I will connect tonight.

Thanks

Alex

They all pop and fart, but the performance loss and increase in consumption is a concern. Assuming that the air filter hasn't suddenly blocked, then looks like a sensor. you haven't had the dummy tank off have you? I seem to remember someone leaving a hose off under there and that causing problems. Did anything show on the GS911?

 

[alex_rsa]

They all pop and fart, but the performance loss and increase in consumption is a concern. Assuming that the air filter hasn't suddenly blocked, then looks like a sensor. you haven't had the dummy tank off have you? I seem to remember someone leaving a hose off under there and that causing problems. Did anything show on the GS911?

GS911 is showing no faults and annoyingly (because it would be the obvious solution) the Lambda sensor looks like it is reading correctly and constantly spikes up and down at idle. The only thing that looks odd (although I have nothing to compare it to) is that the Lambda sensor stays rich for seconds after blipping the throttle.

 

[Mav]

GS911 is showing no faults and annoyingly (because it would be the obvious solution) the Lambda sensor looks like it is reading correctly and constantly spikes up and down at idle. The only thing that looks odd (although I have nothing to compare it to) is that the Lambda sensor stays rich for seconds after blipping the throttle.

When they went on my GSA, the guys at the dealer took a while to work it as no error was showing... You can do a physical check by taking a look at them... they're likely really sooted up. Sometimes, just cleaning it can make a difference.

 

[alex_rsa]

OK, GS911 was initially showing a working Lambda but when I reset all the values it starting only going rich. Blipping the throttle does show Lambda movement so it looks like it is working but I changed it anyway. New Lambda is giving the same readings as the old one - damn.

Bike is super rich, there is actually black smoke (fuel) coming from the exhaust when you accelerate.

GS911 is not showing any error codes.

Dismantled the airbox and removed/cleaned all the sensors. Checked there are no air leaks to the throttle bodies.

Still no idea and it looks like it is a trip to BMW.

 

[harry]

Throttle Position Sensor very likely. Dosen't always show as a fault.

 

[alex_rsa]

GS911 is showing that the TPS is working. Reads 0.8v with the throttle closed and 4.44v when wide open.


My brain is saying failed fuel pressure regulator with the pressure being to high.


The bike is super rich right from cold start so before the Lambda is even working.

 

[alex_rsa]

It's fixed.

I thought I would close off the thread with the solution to help anyone else who has a similar (and seems very rare) problem.

Fuel pressure sensor.

Did the obvious things first, plugs, coils and Lambda with absolutely no change.

Thanks to an article on athe ADVRIDER website advising someone doing an overland trip on some basic fault finding I found out the bike can run without the fuel pressure sensor attached and in fact it ran better without it.

On the GS911 you can see the fuel pressure. Without the FPS connected the reading is over 6Bar (and you get an error light and code), with my sensor connected it was reading 2Bar (and no warnings). I got hold of another FPS and that shows just over 4Bar.

It seems counter-intuitive that low pressure causes over-fueling but it is due to the FPS controlling the fuel-pump. The low reading must of caused the fuel pump to run all the time to try and get the pressure up meaning that too much fuel was being injected all the time.