Fuel Strips (Film type fuel sensor)

[kobus]

I've attached an image showing the reading form the gs911. The left shows the fuels strip idling while the right side shows the fuel strip being polled.

It looks like as long as the computer is turned ON there is a very minimal amount of current going to the heater. Usually, about 2.42mA. Can this vary from strip to strip? What is the "normal" value/range here? The strip heater voltage seems to be very minimal as well at 0.07V. The Fuel Sense Voltage is always 0 on my bike, I'm guessing this is for those equipped with a float, but have no idea. I don't understand the Film Sensor Heating percentage. When the fuel strip is being polled this seems to jump to 62.8%. Is this normal? Why wouldn't it hit 100%? Also when the strip is being read, the heater current jumps to 187.76mA and the voltage to 1.05V.

I'm trying to determine what these values are telling me and if they are withing the accepted ranges as I believe my fuel strip is on it's way out again.

Normal ranges (for fuel strip):
Fuel heater current: 0- 300mA
Heater voltage: 0 - 1V
Fuel sense voltage: 0 - 0.5V
Film sensor heating (this is PWM): 0 - 100%
 62% looks normal (100% would be full on). Ultimately it's up to the fuel sense algorithm when and how it heats and measures the fuel level.
This will also vary from strip to strip (that's why there is a calibration procedure).

If your fuel sense voltage is 0V all the time, there is something wrong with the strip (sense circuit is open-circuit?).

Also, is it possible to show the resistance reading from the sensor circuit?

No, we can only show what the ZFE reads.

[deciacco]

Kobus,

Thanks so much for your response.

If your fuel sense voltage is 0V all the time, there is something wrong with the strip (sense circuit is open-circuit?).

I tested the two center leads on the strip. With the multimeter set to 20k ohms it reads 2.55. This tells me the sensor circuit is not open, but indeed the fuel sense voltage is 0V all the time.

[kobus]

Please attach an AutoScan of your bike, view the realtime values and then send the logs (Tools->Send Todays logs) so I can double check the fuel sense value for your particular bike.

Thanks
Kobus

[deciacco]

Kobus,

I sent two logs, the second one has the real time values in it. Sorry.
See attached for the autoscan.

Thanks!

[v-man]

2010 R1200 GSA

WB1048001AZX65246

Fuel strip replaced ONE time

[Jughead]

2006 R1200GSA - VIN: WB10382066ZN91388

Film Type Fuel Sensor - Never replaced.

Autoscan attached.

[StephanT]

yes, the general feeling is that this is most prominent in North America... lots of speculation.. but one of the theories is the Ethanol content...

[juhhyto]

I know there is not enough samples, but in Finland we have a 95E10 and 98E5. E is ethanol and 10 and 5 are %. Many drivers use the 98, engine is somewhat smoother with it, even though it is more expensive.


-juha-

[Inspector Gadget]

Hi,

Just sharing my 5 eurocents;
We also have a lot of complaints of faulty film type fuel-sensors too, over here in the Netherlands.
If the bike is under warranty, 9-out-10-times the fuel-sensor will be replaced under warranty too.
However, BMW ceased warranty-replacements for a period of time due to excessive failures, so I'm told.

But often the fuel sensor ultimately keeps failing in the long run, eventually.
I have heard from users who are up to their third replacement within less then a year!

On my 2007 R1200RT the fuel level is permanently indicating full, likely because the fuel evaporated due to fuel-cap not sealing properly anymore and me not being able to ride it for a very long time.
Meaning, that the calibration is off/lost. (read: no miles ridden and fuel-level has changed dramatically, according to the "smarts" of the ZFE.

I'm also considering replacing the film type fuel sensor with the mechanism for a float-type, I can get the float-type from a scrapper for reasonably cheap. (from an 08/2010 R1200RT)

My thoughts are, as the GS911 can do the calibration, with the float-type installed (which is also resistance), I could try to get the ZFE to understand the resistance-value of the floater-type instead.

I have searched with g00gle to find if anybody endeavoured that already, but not found anything.
So, I could be very wrong.

[kobus]

My thoughts are, as the GS911 can do the calibration, with the float-type installed (which is also resistance), I could try to get the ZFE to understand the resistance-value of the floater-type instead.

I have searched with g00gle to find if anybody endeavoured that already, but not found anything.
So, I could be very wrong.

You would not be able to replace the fuel strip with a float.
They operate very differently. While the float is purely resistive, the film strip has a heating element and a measuring element that is current sourced. The ZFE, cluster and probably engine controller would need to be re-coded for a retro fit to be done, but I'm not even sure even if BMW can retro fit it (otherwise they would have done it because of all the failures by now?).

[Inspector Gadget]

Good point, thanks!!
And that is of course why they are also connected to different ports on the ZFE.

So, I would need to take the floater (resistor value), build electronics to convert that to current-output (read: need a small voltage) that is within the range that the ZFE expects from the film type fuel sensor.
Assuming that the floater is resistive-wise similar to the film type sensor (logarithmic or linear)

I need to put my creative cap on.

[StephanT]

indeed, something like that...

The bike models with Float vs Strip have different wiring harnesses.. as they use completely different pins on the ZFE..

best
Stephan

[Inspector Gadget]

Thanks, I also noted that on schematics I have (from the Haynes manuals, both versions, thus also DOHC), even though their wiring diagrams are perhaps not completely accurate and/or not without faults.
(and the Haynes manuals are not fully complete/accurate either, but that is a different discussion)

In essence, it might be doable, it is a matter of how much efforts are involved.
Next to being very careful, not damaging the ZFE.

[Haakon]

Just a question: How many bikes have this problem?
If all or many of the "fuelstrip" bikes have this problem I would think some firm would see a good business opportunity?
It can not be too dificult to make a digital conversion unit to fake the strip signals, with a float sensor installed?

There seems to be a limited number of bikes that have this problem?
As others have mentioned, can it be a fuel related?
Thinking of ethanol fuels.
Water residues in the fuel.
"Old" fuel- bikes not used very often.
... whatever
Haakon
-----------------------
New reply posted while I was typing:
Please do NOT trust any of the schematics, BMW`s or others!
I have several chematics for MY bike, and all have "faults". Wire colors and whatever.
I believe BMW did modifications to the wirings more often than we change underwear!!
 

[Inspector Gadget]

On the "social media" that I'm active on (mostly forums for 1200GS & 1200RT) the fuel-strip failure is a hot topic, next to 2010's 1200RT switches.
(the handlebar switches also fail a lot, likely due to cracks in the flexible print to which the switches are mounted)

Fuel-strips fails a lot.
So much that BMW halted warranty-replacements last year for some time.
And probably why BMW replaced the fuel-strip with the floater-type since production-year August 2010 for the R1200RT. (just a wild guess from my side).

In the Netherlands, Ethanol is not yet commonly added to the premium (95 ROZ/RON and above), so I would rule it out that Ethanol is the culprit in our cases where the fuel-strip fails. (sometimes repeatedly).  But that is my take on that situation.

From what I have read and understood, 2 possible situations seems to be causing premature failure:
- The fuel-strip apparently have some electronics sealed at the top of the strip and apparently the sealing/encapsulation is not up to spec, causing fuel to reach the electronics and causing havoc.
I have not seen a fuel-strip in real life so I'm not sure about that.

- Miniature (micro)cracks develop along the measuring part of fuel-strip, causing disruption in the (complete) resistive path or incorrect (out-of-spec/calibrated) signals/values which the ZFE can no longer properly interpret.
From what I understand, due to mechanical load/vibrations.
This is, according to many on the different forums, resolved by micro-welding these cracks via the high-voltage output of a piezo lighter.
I know personally of a few people who had issues with their fuel-strip, build the outlined micro-welder out of a lighter and indeed resolved their problems that way.

I'm currently chewing on (read: contemplating) purchasing a complete fuel-unit with the floater-type sensor from a dismantling company to see if mechanical replacement is remotely possible and then consider what would be involved of converting the resistive output (= floater) to current-output (= fuel-strip). In very simple black-and-white it would require some voltage.
According to Ohm's Law:
U (voltage) = I (current) times R (resistance).
Current is what the ZFE expects/measures from the fuel-strip, resistance is what the floater-type will provide, so it would then be voltage to make that happen.

Mind you, from what I have read & understood from how the ZFE works with the fuel-strip, the voltage from the ZFE is modulated (PWM) and thus also the heating, and it lets to be seen if the measurements via the fuel-strip is something linear or logarithmic or something else/combination to what the ZFE interprets as the various fuel-levels.

So, it would also be the algorithm that needs to be found out when the ZFE is the fuel-strip version.

Somebody else already played with that on one of the US forums, and came up with this;
http://bmwsporttouring.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=770085&page=6

As for trusting schematics, wiring diagrams and so on;
I agree 100%!
I have the official BMW RepROM's and even those contain mistakes and omissions. Yikes!
Thanks for reminding me, it just turned Friday overhere, time to change my underwear again. (Joke!)