Low fuel warning light on K75s

[canazei1200]

Mine always comes on at 125 miles ignored it today got home with trip showing 175.50 odd miles with that annoying red light on. any way to change when it comes on or am i stuck with ignoring it. Thanks.

[motodude]

You may be able to remove the filler cap, reach in and bend the arm the floaty-thingy is attached to.  If you bend the floaty-thingy end down, the light will come on, "later".

Tom

P.S. I'm not telling you to do this. (disclaimer)

[dfx]

Just got my 85 K100RT back on the road. I've fitted a second-hand instrument unit as my speedo was playing up. I've also worked on the injectors and air filter so had the petrol tank off. Did a 10 mile test drive, came back to the bike to go home and found the red fuel warning light was on. The orange one hadn't come on. Filled up straight away. Next day, at the end of a 30 mile ride, I noticed the same light on again. There was plenty of fuel so I just ignored it. So I'm wondering should I try putting the old instrument unit back or could I have done something wrong when I took the tank off?

[Billk]

I have a 1995 K75. When the trip meter his 175miles I fill her up. If I lose track of the trip meter I fill her up. When in doubt filler her up and set the trip meter to 000. I have a sticker by the RPM gage that reads 175 to remind me. My gas light starts coming on intermitantly at about 65 miles, on and off and on and off?... I learned to live with it. I suppose it can be fixed.

[Motorhobo]

I have a 95 and a 94 k75 and the light always comes on app. 135 miles after a fill on both. Sometimes I run it till 160 on the trip meter but never more as the tank is always bone dry after 160. Personally I think 175 is really pushing it with the standard 4-ish gallon tank. Even if you assume 45+ mpg, at 175 you're on fumes. Legend has it that  running on empty is the worst thing you can do to your OEM fuel pump.

Just sayin'...

[Photog]

Running very low is bad for any fuel pump, OEM or otherwise. They are cooled by the fuel, so, a low fuel level means the body of the pump is operating in air.

[HYPERR]

I have a 95 and a 94 k75 and the light always comes on app. 135 miles after a fill on both. Sometimes I run it till 160 on the trip meter but never more as the tank is always bone dry after 160. Personally I think 175 is really pushing it with the standard 4-ish gallon tank. Even if you assume 45+ mpg, at 175 you're on fumes. Legend has it that  running on empty is the worst thing you can do to your OEM fuel pump.

Just sayin'...

I thought the tank held 5.2 gallons of fuel...

[dfx]

I'll just have to start by replacing my old instrument unit with the duff speedo.

[Motorhobo]

According to this thread, post-93 k75s have .5 gals lower capacity than earlier ones.

http://forums.bmwmoa.org/showthread.php?49822-Intro-to-the-K75-Motorcycle-101-Fuel-Capacity

Also, if you have replaced the OEM pump with an aftermarket one such as the one for the Ford Escort, the pump might not reach as low into the tank and might affect the useable capacity of the tank. I don't know but I've always thought my tank held 4.6 or so gals and after 160 mi I've always thought better to fuel up than run the pump unsubmerged.

I've never run out of gas to test the useable capacity...don't plan to either.

[billday]

On my '85 K100 (which is a different system from the newer machines), the yellow warning light sometimes comes on as I'm pulling out the the gas station. With a full tank of gas. It's just useless -- I always go by the trip odo.

[The Mighty Gryphon]

+1 on the trip odometer.  I fill up at about 200 miles on my K75RT, takes about 4.3 U.S. gallons which leaves about 1 gallon in the tank.  Low gas light comes on about 205 miles.  Trip reset is part of the fueling ceremony.

Bike gets a pretty consistent 46 mpg with my commuting, it only varied by 1.5 mpg all last summer, even on trips and weekend rides.

I put a fuel cooler on the bike over the winter lay up.  I figure with cooler gas in the tank, the cooling of the pump will be better with the cool gas going through it at low tank levels.  I also think that not having hot gasoline in contact with the rubber bits in the tank will extend their life expectancy as well.

[dfx]

It's definitely a fault as before the red light would come on going up hill or round a bend then go out when the bike straightened up. Now it just stays on.

[HYPERR]

According to this thread, post-93 k75s have .5 gals lower capacity than earlier ones.

http://forums.bmwmoa.org/showthread.php?49822-Intro-to-the-K75-Motorcycle-101-Fuel-Capacity

Also, if you have replaced the OEM pump with an aftermarket one such as the one for the Ford Escort, the pump might not reach as low into the tank and might affect the useable capacity of the tank. I don't know but I've always thought my tank held 4.6 or so gals and after 160 mi I've always thought better to fuel up than run the pump unsubmerged.

I've never run out of gas to test the useable capacity...don't plan to either.

Just as an example, right at this moment my trip meter says 171 miles.  The low fuel light has not come on and I just shook the bike and from the sound of fuel sloshing around in the tank, my gut tells me there is anywhere from 1.5 to 2.0 gallons of fuel still in there.  Based on the fact that I get anywhere from high 40s to low 50s as mpg, that sounds about right. 

I never tested it intentionally but back in '95 or '96, I distinctly rememeber that on my 1995 K75A/3 that I had back then, as I was in middle of nowhere looking for a gas station, I could start to hear the faint sound of the fuel pump whining when I hit 240 miles on the tripmeter; clearly indicating that it was no longer submerged.

[Conrad325i]

On the first tank I put thru mine, I ran out of fuel waiting on the light to come on... Girlfriend had to bring me gas. i dont plan on trying to fix it as long as my fuel pump is still getting power.
Previous owner had crammed the floater arm wrong way thru the tank and I think its bent so that the wiper doesnt make contact anymore. I just look in the tank before I start it and check my level visually as I deleted the little flapper cup when I rebuilt my gas cap... my cap was kept shut using duct tape when i bought the bike....
(If anyone has a defective lock cylinder for their tank i have designed and 3d printed a part that allows the tank to be opened without a key.)