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1Back to top Go down   When does the low fuel lamp come on? Empty When does the low fuel lamp come on? Tue Mar 21, 2023 7:18 pm

duck

duck
Life time member
Life time member
Anybody ever measured the ohms on the yellow fuel level wire when the low fuel lamp circuit white wire gets continuity to ground?

I have an annoying K75S where the idiot light comes on when there's two gallons left so I want to adjust it to come on with five liters left like it's supposed to.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

92KK 84WW Olaf

avatar
Life time member
Life time member
duck wrote:Anybody ever measured the ohms on the yellow fuel level wire when the low fuel lamp circuit white wire gets continuity to ground?

I have an annoying K75S where the idiot light comes on when there's two gallons left so I want to adjust it to come on with five liters left like it's supposed to.

I found it started to flash after using 13 litres. Constant on after using about 14 litres. On my K100RS I have managed to run the tank down to take over 20 litres without running out.

I would do a refuel when it comes on and see how much it takes.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 54,800 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.
1983 K100RS 0004449 Odette 55,000 miles. Sprint fairing

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

duck

duck
Life time member
Life time member
If nobody knows then my plan is to carry a multimeter in a bike where the light comes on at the "right" time and then pull over right away to measure the yellow wire ohms.

Then when I have the "bad" fuel level sender on the bench I can adjust the little gear wheel so that the low fuel wire triggers at the same resistance of the yellow wire as the good one.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I seem to recall that RBM has written up and posted in a thread here a procedure for calibrating the fuel level sender and the low fuel light.  I think it was about 2-3 years ago.


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Present:
1994 K75RT
1991 K100RS


Past:
1988 K100RS SE
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

duck

duck
Life time member
Life time member
Point-Seven-five wrote:I seem to recall that RBM has written up and posted in a thread here a procedure for calibrating the fuel level sender and the low fuel light.  I think it was about 2-3 years ago.

Already checked that thread and it's not there, just the max and min ohms.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

caveman

caveman
Platinum member
Platinum member
I'm lazy and had that same annoying light so I just bent the float arm. It now comes on with 3-4 quarts left, 30 to 50 miles till empty.

    

Laitch

Laitch
Life time member
Life time member
duck wrote:If nobody knows then my plan is to carry a multimeter in a bike where the light comes on at the "right" time and then pull over right away to measure the yellow wire ohms.

Then when I have the "bad" fuel level sender on the bench I can adjust the little gear wheel so that the low fuel wire triggers at the same resistance of the yellow wire as the good one.
The ohm range seems only part of the equation; the angle and flexibility of the float wire could be the other. Considering the likely variability of the float wire's angle among senders depending upon whether the wire was made at the start of the work week or its end, the level of worker sobriety and attention given to its bend angle, the calibration of the machine bending it, the flexibility of the wire in each production run, and the effect of immersion in fuel for years on its flexibility. caveman's strategy seems to be the way to go.  I, too, was a Brick wire bender when the time came, but manipulating the sender's gear wheel still has a mysterious attraction to me. thanks to robmack. Smile   In a way, it's unfortunate just bending it worked so well. When does the low fuel lamp come on? 177381

In 2012 Inge wrote that the range was 3.5Ω to 110Ω but indicated he hadn't verified it because he had better things to do.  Smile  I'm looking forward to your results.  cheers

    

duck

duck
Life time member
Life time member
There's very little flexibility in the float "wire." It's pretty hard steel and bending it by hand, even out of the tank, would take quite a bit of force.

They were produced in a quality controlled manufacturing environment so the bend angles are very consistent from unit to unit. They are not one-offs built in somebody's garage.

Any variations between units would be caused by corrosion and wear.

FYI: I measured a fuel level sender (late version) the other day  and the range was 3-108 ohms.

RBM's very informative mother of all fuel level sender threads shows readings pf 2.3-114 ohms.

I'll add to this thread as I obtain more data.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

Laitch

Laitch
Life time member
Life time member
duck wrote:There's very little flexibility in the float "wire." It's pretty hard steel and bending it by hand, even out of the tank, would take quite a bit of force.

They were produced in a quality controlled manufacturing environment so the bend angles are very consistent from unit to unit. They are not one-offs built in somebody's garage.
Consider bumping up your dumbbell workout regimen and also using needle nose pliers. Smile

The Chevy Vega was built in a "quality-controlled environment," too. When does the low fuel lamp come on? 177381

    

duck

duck
Life time member
Life time member
The Vega? You could not have chosen a worse example of quality control. Chevy Vegas were crap due to multiple engineering issues and, as a low end car, GM sought to build them as inexpensively as possible.  Not to mention that quality control among US auto makers in 1970 was simply horrible and didn't improve until later when they started employing William Deming's statistical approach to quality control in order to be able to compete with Japanese reliability.

Do you think that the rest of your K bike is also built like a Vega or just the fuel level sender?

The FLS arm is difficult to bend because it is hardened (probably  tempered) steel. It's really not a good idea to attempt to bend tempered steel like the rod that holds the FLS ping pong ball. Since the steel is tempered is not very ductile and can break. Have you ever broken a cutting knife? It will bend some but at a certain point it just snaps before bending any more.. It MAY be possible to permanently bend the FLS float arm a little if you're careful but I choose not to test that theory and needlessly destroy a $350 part.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

Laitch

Laitch
Life time member
Life time member
duck wrote:It MAY be possible to permanently bend the FLS float arm a little if you're careful but I choose not to test that theory and needlessly destroy a $350 part.
It IS possible to bend it; both caveman and I—and who knows how many others—have overcome BMW's space-age, highly-tempered, SWAT door entry ram-quality, steel float arm to effect the tiny change needed to give us what we thought we wanted. In my case, there was no damage to this expensive component probably because of the highly-sensitive fine motor skills I've developed in chainsaw operation. caveman must have similar hard-won ability.

As far as lessons from W. Edwards Deming go, Toyota was listening, but GM must have been talking in class and checking its Facebook pages because it led the manufacturer pack with 671 separate recalls from January 2000 to July 2022, according to the folks at BANKRATE. By now it's probably wholly-owned by the PRC. Smile

Nonetheless, you'll likely be gratified to know that I fully support your research. cheers

    

duck

duck
Life time member
Life time member
Good to know that it can be bent.

Could be easiest solution for low fuel light on a K w/o a fuel gauge.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

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