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Thread: fuel lights

  1. #1
    Registered User R75rider's Avatar
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    fuel lights

    Are the fuel warning lights on an 85 K100 prone to have any certain thing go bad? While I was almost running out of gas today I was reaching under the tank hunting the petcock to switch to reserve... never found one.

    I was lucky enough to make it to a Texaco station before the engine quit. Since I still can't find a petcock I better check into fixing the warning lights!

  2. #2
    Registered User kioolt's Avatar
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    I can't tell you about the fuel lights but there is no fuel petcock. I don't believe any fuel injected bike have or need a fuel petcock. When you turn the key off the fuel pump turns off. That accomplishes the same thing.
    2004 R1150RT 151,500 miles , 1991 K100LT 128,000 miles, 1982 R100RT 106,900 miles
    Total 386,400 BMW miles
    AMA,BMWRA,BMWMOA
    The cheapest thing on a BMW is the nut that connects the handlebars to the seat.

  3. #3
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    To expand on R75rider's answer:

    Since there is not a petcock, there really isn't a reserve as well. On the 85s, you have one light come on at one level and then the next comes on at another (I don't remember the exact values--something like 6 liters and 4 liters for the two lights).

    On my 88, one of the lights was replaced by the ABS light and I know I have 20 miles when the fuel light comes on.

    The first thing to check is the bulbs themselves. IBMWR has good articles on how to get inside the instrument cluster and these are standard automotive bulbs.

    http://www.ibmwr.org/ktech.shtml
    '88 K100RS ABS

  4. #4
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    Push your K bike once to the nearest gas station and you'll never run out of gas again.

    Steve

  5. #5
    Former Club President DonHamblin's Avatar
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    Exclamation Lights

    Randy,

    On the "K's" there is a float inside the tank (later included a guage) as part of the fuel pump assembly. That's what triggers the lights. When you change your fuel filter (if you haven't done that yet, I would recommend doing it real soon - and carring a spare in case it gets filled by some "buget" gas) you should see the float assembly. Try not to "bang" that float while changing the fuel filter or the "low fuel light turn on point" will change.

    On my 85 K100RT I "lost" the bulb out of the yellow "7 liter" light and kept the red "4 liter" light. That would always give me an easy 35 miles to find a gas station. Running in the "5 grand sweet spot" and above (on an '85) could put you real close to that 35 miles.

    So that "around a gallon" acts like a reserve.

    Ride safe,
    Don

  6. #6
    Registered User R75rider's Avatar
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    Thanks for the answers everybody. It would be nice to have at least the 4L light as something to go by. I may tackle pulling the cluster this weekend if possible. I found the description over on that other site how to take it apart. Until then I'll do like the old days and open the cap and just look. After this tank of fuel runs out I'll know how many miles to go on the trip meter before I need to look.

  7. #7
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    On my 1988, I average 160-180 miles before refueling, depending on the type of riding I'm doing.
    '88 K100RS ABS

  8. #8
    K1200RS spikethebike's Avatar
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    Get a fuel plus.

  9. #9
    A bozo on the bus deilenberger's Avatar
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    Re: Lights

    Originally posted by Don Hamblin
    Randy,

    On the "K's" there is a float inside the tank (later included a guage) as part of the fuel pump assembly. That's what triggers the lights. When you change your fuel filter (if you haven't done that yet, I would recommend doing it real soon - and carring a spare in case it gets filled by some "buget" gas) you should see the float assembly. Try not to "bang" that float while changing the fuel filter or the "low fuel light turn on point" will change.

    On my 85 K100RT I "lost" the bulb out of the yellow "7 liter" light and kept the red "4 liter" light. That would always give me an easy 35 miles to find a gas station. Running in the "5 grand sweet spot" and above (on an '85) could put you real close to that 35 miles.

    So that "around a gallon" acts like a reserve.

    Ride safe,
    Don
    Don (and Randy)..

    The FYK ('85) years and prior had NO float assembly in the tanks. Instead of a mechanical float - BMW used two thermo-resistive sensors, which work great in a lab - and awful on a bike. Starting in '86 model year - they went to a float assembly (and changed lots of other things in the tank and instrument pod and wiring - so a retrofit isn't really possible).

    The one on my old FYK would randomly turn the lights on and off, to the point that I took the bulbs out.

    A Fuel+ is the real answer, unfortunately Dave W has discontinued the K specific one in favor of a more universal design that hasn't been released yet. You might have some luck advertising looking for a used Fuel+ on the MOA or IBMWR marketplaces.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  10. #10
    Registered User R75rider's Avatar
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    I read the post about the Fuel Plus a few days ago. I checked it out on the web and the price is way out of my range, so I didn't bother commenting on it.

    I'm sure it's a fine addition or replacement for someone who could pay that price. I'm just too stingey right now with vacation coming up and the maintenance i'll have to do to my truck before the trip. But that's beside the point. Right now i'll just have to be happy with peering into the tank every few days.

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