K100 Fuel sensor outputs

[Fanum]

My brick has (like most) two lights for low fuel......one is supossed to come on at (I can't remember now exactly, but let's just say) 20 or so miles, the other at 10

The longer distance warning doesn't come on.

The shorter distance red one does, but sod's law says that it it comes on within 3 miles of work, I don't have enough fuel to get home or back to the petrol station here.

I could fark about with the other light to get that working, but I'd rather put in a gauge....Particularly as I have gauges and a whopper of a fairing to mount on in properly

Now, I know that the RT and LT variants had gauges as standard, so I'm wondering if the output from the fuel sender is a normal varying voltage from a slide type resistor like on the GS......or if they put in a different resister system where maybe there is a contact 2/3 or the way up the sliding resistor dial to trigger the first warning light, and another the equivalent of ten miles from the top of the slider that switches the 2nd warning light

Anyone know please?

 

[DrFarkoff]

Back to basics sonny!

SET TRIPMETER! when ya fill up

If you take the filler neck out as if you were changin the filter you could maybe bend the arm on the float?

 

[Ogmios]

apparently*
older models had the two lights working /later ones just the one. (Dr F-can you confirm?)
Like Fanum, i would much prefer a reasonably accurate guage or better yet a feckin reserve position on a tap. (yes, i know i know - no can do on a fool injected Bike )
i've thought about this and reckon bending the yoke in the tank is probably the only option.

*wtf do i know?

 

[Fanum]

Back to basics sonny!

SET TRIPMETER! when ya fill up

If you take the filler neck out as if you were changin the filter you could maybe bend the arm on the float?

Fuck the basics......and I often can't afford to 'fill up'......a splash and dash with the fiver I have in my pocket is sometimes necessary ....you can't reset the trip meter by a fiver's worth !

I haven't delved inside the tank yet, not TBH have I even bothered checking continuity through the non-functioning warning bulb circuit.....

As in OP, even if I can get the first warning light working (should be pretty easy) I'd still rather have a gauge........the brick has a small tank and I would prefer an analogue gauge than a 'digital' (in the sense that it's on or off') warning light system

Cheers though

 

[DrFarkoff]

I know what you are saying but Still basics Fanum

Stick in a tenner or a fiver app mpg 35

so a fiver you need to be looking at 30 miles and a tenner looking at 70 miles (ish)

You know what I mean don;t cha?

Og as you said earlier that's what I understand happens

 

[MikeP]

Bill, I fail to see what you hope to achieve with a gauge that you cannot already do with the trip and the fuel warning lamp.

The amber fuel warning lamp was set to 7 litres, the reason why it was deleted is that as you've probably already found with the red 4 litre light, going uphill with more than four litres has the light coming on. Now imagine how bloody annoying that amber light is at night when you start to climb a gradient with half a tank and the light comes on.

Given that any gauge will work from the same float in the tank that triggers the warning lamp(s), all that will happen is that the fuel gauge will take a dive - just as it does on the bikes fitted with BMW's own fuel gauge.

The only thing the gauge on my K1 is good for is to balance up the useful temperature gauge on the other side of the bike. The rest of the time I use the trip and the four litre warning light (and then only when the bike is level and upright long enough to believe it).

 

[Fanum]

I know what you are saying but Still basics Fanum

Stick in a tenner or a fiver app mpg 35

so a fiver you need to be looking at 30 miles and a tenner looking at 70 miles (ish)

You know what I mean don;t cha?

Og as you said earlier that's what I understand happens

Bill, I fail to see what you hope to achieve with a gauge that you cannot already do with the trip and the fuel warning lamp.

The amber fuel warning lamp was set to 7 litres, the reason why it was deleted is that as you've probably already found with the red 4 litre light, going uphill with more than four litres has the light coming on. Now imagine how bloody annoying that amber light is at night when you start to climb a gradient with half a tank and the light comes on.

Given that any gauge will work from the same float in the tank that triggers the warning lamp(s), all that will happen is that the fuel gauge will take a dive - just as it does on the bikes fitted with BMW's own fuel gauge.

The only thing the gauge on my K1 is good for is to balance up the useful temperature gauge on the other side of the bike. The rest of the time I use the trip and the four litre warning light (and then only when the bike is level and upright long enough to believe it).

So.......

Is the signal from the tank sender unit an analogue style variable voltage, or is it a digital 'on' or 'off' signal?

 

[MikeP]

So.......

Is the signal from the tank sender unit an analogue style variable voltage, or is it a digital 'on' or 'off' signal?

Rip the fucker out and analyse it on your walk to work and back.

 

[turnipbmw]

suggests here that they work on a different principal