Faulty Fuel Level Strips

Discussion in 'GS Boxers' started by ARG, Jan 22, 2012.

  1. JohnnieWinona

    JohnnieWinona ol'cowboy

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    Joel, i wrote way back in the early pages, my right fuel line came unclipped (somehow), and i thought it was the strip again. i thought all was well after i took the strip out, cleaned and reinstalled, reclipped my right fuel line. It sort of worked. I'm almost out of warranty, and my dealer is tired of replacing the strips in my ADV. How do you reset, or recalibrate????
  2. EddyQ

    EddyQ Dreamer . . .

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    Are we certain there are two independant circuits? Anyone ohm out a good strip to see if there was a connection from the heater circuit (pin 1 to 4) to resistor circuit (pin 2 to 3)?
  3. GS Addict

    GS Addict Pepperfool

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    I measured a known good one and the two circuits were isolated from one another.
  4. TXjames

    TXjames High Sider

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    I hate to say it but I think we're wasting our time here fellas. A buddy read that this has already been attempted by some guys on bmwst. He didn't bookmark the thread and I haven't been able to find it but they were unsuccessful and came to the conclusion that it will not work with a simple resistance.
  5. EddyQ

    EddyQ Dreamer . . .

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    I've spent a bit of time over at BMWST and don't recall this exact test being a failure or even tried.
    There is a case where someone replaced the strip and didn't bother to calibrate. The new strip resulted with very low fuel indication.
    http://bmwsporttouring.com/ubbthrea...65789&Words=fuel+strip&Search=true#Post732860

    So, if I would guess what your issue is, the resistor value isn't close enough to what your old strip had.
    Maybe the heat transfer is different or simply the tolerance is too great.
  6. OldBob

    OldBob Adventurer

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    I wonder how the resistance (at start-up) changes between say -20F and +120F, ambient temperatures to which the bikes can be exposed. I'm starting to suspect that an ambient temperature "correction" is part of the equation. If so, then start-up (with a full tank) resistance is variable. Any resistance that we introduce would have to be in synch with the ambient temperature.

    Bob
  7. OldBob

    OldBob Adventurer

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  8. TXjames

    TXjames High Sider

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  9. TXjames

    TXjames High Sider

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    The mystery has been solved! Here are the details as I posted them on the bmwst 'Crossing fuel gauge wires' thread...

    RoSPA_man really made an outstanding discovery when he realized that the multimeter enables the circuit!

    After I was able to repeat his results on my bike I was discussing them with smiller. He locked on to the very small voltage generated by the meter (mV) and recommended wiring the positive side of the fuel strip circuit to 12V with a very large resistance between to emulate the meter. It turns out that a 1M Ω resistor comes very close to supplying the same voltage as the meter. With this high resistance there is very little current flow; a mere 0.001mA (yes, one or two micro Amps). With that little current it may not even be necessary to ignition switch it.

    Couple this small voltage with the 2k Ω that it takes for the tank to read full and you have an infinite full tank and, more importantly, no error code flashing at you constantly! Here is what the final circuit looks like (in my kindergartener¬ís mind):

    [​IMG]

    This is it people! We no longer have to repeatedly pay BMW for their poor design!!! I give you... The Infinite Tank
  10. TrollGSA

    TrollGSA Adventurer

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    Well done. I shall do this myself. Nice work.
    So what wattage resistors?
  11. tanneman

    tanneman I'm no Adventurer

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    First time post, so hello to everyone.

    On pg 6 the proper neat solution has been posted.

    [​IMG]
  12. TXjames

    TXjames High Sider

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    Sorry. I forgot to update over here. I will probably start a new thread with the solution written up more formally once I finish testing.
  13. ceasarfelix

    ceasarfelix 2009 R1200GS

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    Someone could sell a lot of these things if they put together a simple unit for us novices that can be spliced in wire-to-wire:trp
  14. drmajor

    drmajor Been here awhile

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    I would like to get in on the new info when you have it ready...

    Does the 2k and 1m resister just fool the bus that there is fuel and thus get rid of the FUEL warning?
  15. kk3an

    kk3an Adventurer

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    I replaced a fuel level sensor in a 2009 R1200GS last evening - bran new sensor & uncalibrated. Filled the tank to 5/8, and the gauge on the bike read 5/8. Filled the tank up full and the gauge read full. Fired up the bike and idled for 10 minutes, and the gauge remained reading full, as it should.

    Prior to turning the key for the first time after the sensor install & with a bone dry tank, I cleared the computer (battery cables shorted).

    The bike has 39,900 miles. For a short time prior to the sensor going bad, I had been transferring fuel - while riding - successfully from an auxiliary fuel cell. Early on after the sensor failure, I didn't know if doing this "on-the-fly" transferring would have been a contributing factor, but the more I think about it, I don't believe this would have any effect on the sensor itself.

    If anyone has a different feeling about that, please let me know, but I think it's just a coincidence - mainly because the first few tank transfers went just fine.

    Dan
  16. cjack

    cjack Been here awhile

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    I take you are saying it doesnt need the recalibrating. I believe BMW agrees and they no longer require it.
  17. cjack

    cjack Been here awhile

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    The heater is about 35 ohms...so you are saying that the absence of heater current is acceptable?
  18. kk3an

    kk3an Adventurer

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    In just the two rough measurements I made (5/8 and full tank), there seems to be no calibrating needed - at least in my case.

    Dan
  19. TXjames

    TXjames High Sider

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    Yes. The 2k resistor replaces the fuel strip when its reading a full tank. The 1M resistor simply supplies the small bias voltage necessary to make the circuit work.


    No. The diagram shows the heater still connected. I have spoofed the heater using a similar 1W resistor but I have not completed testing. It is possible though.


    If anyone knows where I can source the male side of the 4-pin connector please let me know! I could produce a plug-and-play solution that would require no electrical knowledge and provide it for the community.
  20. Bill the Bong

    Bill the Bong Supern00ba

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    I have had a replacement fuel strip on back order for a couple of weeks now. My dealer assumed that they are making changes to it. However, yesterday I got a call stating that BMW has developed new software to drive the fuel strips. My bike goes in next week. We'll see...