Post-Fuel-Pump-Replacement Issue - BMW F800 Riders Forum & Registry



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  1. #1
    Points: 9,335, Level: 66

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    David
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    '09 F 800 ST
    Re: 2009 F800ST, 12K miles: At the end of the 2019 riding season I had a breakdown. I traced it to a non-functioning fuel pump. Bought a quality aftermarket pump (High Flow Performance), but suspected given the low mileage, when I removed the original to replace it, that it was more likely the corroded in tank connectors. Replaced the pump anyway, and carefully routed the wiring and hose per the pre-repair alignments using the photos I took before disassembly.

    After replacement, and two subsequent removals and refitting, the fuel gauge refuses to operate properly. After a fill-up It shows full until about 110 miles, then suddenly reverts to normal operation. I removed and tested the movement and resistance of the float mechanism, no problem, and again verified that there is no interference from the hoses or wiring, at least not when “dry” on the workbench. So I’m left to conclude that the float must be somehow very slightly hanging on the side of tank until the fuel level gets low enough to allow a bump in the road to jar it loose. I’ve tested and re-tested this, and since that performance is consistent I don’t really have a problem. But things not working annoys me.

    I wonder if anyone else has had a similar issue and might comment before I once again remove the unit in an attempt to make it work properly.

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  3. #2
    bmwroadsterca's Avatar
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    I am not that familiar with the ST but on the GS that would be absolutely normal due to the fact that the float can only sense the bottom half of the tank behind the engine and not the top half extending upward at an angle under the seat.

    Sent from my SM-G950W using Tapatalk

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  5. #3
    Closterman's Avatar
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    Martin
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    '07 F800 ST
    What you describe is normal operation of the fuel gauge. I have a 2007 ST.
    When full you will notice this sign > on the left of range. It means «*greater than*». Mine is in kilometres and will usually show 195 to 200 for the first 80 to 100km ridden on the tank. Then the > disappear and the actual remaining range will start winding down.
    The reserve light will lit at 70km remaining.

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  7. #4
    ccramerusc's Avatar
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    Cramer
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    '08 F800ST
    The owners manual can be very informative.
    https://ownersmanuals2.com/bmw/f-800...s-manual-59142

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    08' F800ST- side panniers & Shad SH45 top case, Russell Day Long seat, MRA Vario Windscreen, SW Motech crash bars, ZTechnik exhaust, PC-8 fuseblock, Stebel Nautilus horn, Throttlemeister throttle lock, SW Motech handlebar risers, LED fog lights, highway pegs 

  8. #5
    Points: 9,335, Level: 66

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    '09 F 800 ST
    Thanks. If you are correct about this, then I really don't have a problem. Just seems incredibly strange to have a fuel gauge that only registers through part of its range. But, then, BMW electrical glitches are why I swore I'd never buy another one after my K100. But I did.

  9. #6
    MGD109's Avatar
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    '13 F800GT
    GT is the same only measures bottom half of tank, the dealer said it was due to the complex shape of the fuel tank not easy to relate the height of the fuel in the tank with the volume that's actually left in the tank.
    In the Garage 2013 BMW F800 GT,1994 BMW R80 RT,1986 BMW R80 GS,1999 Yamaha SR125
    Sorley missed Honda TLR200
    Enjoy the ride 

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