Fuel Light not working

George_Pap · 1 Fuel Light not working Tue May 15, 2018 2:44 am

George_Pap

Silver member

Number of posts : 185

Hey all. My K100RT resurrection project reached a 75% of success. I m really happy, a bit more poor but happy Smile

Rode it for about 600km and it gets better and better. So far.
My challenge now is to get fuel lamp to lit.

The story
My bike had the early instrument with the 7 screws and the 7L + 4L lamps. It also has as you can guess the early fuel sender ( electronic stick )
When received the bike 7L and 4L were working properly.
Due to a short circuit that destroyed the green plug and the ribbon pcb bellow it I had to replace the instrument cluster though with an 1987 K75 one. The one with round pins and unfortunately only the 4L lamp.
By suggestions of great guys here i swapped the fuel sender pcb of the "new" instrument with the one of the old instrument. Since it was not working and due to replacement of the fuel pump and fittings i did purchased a used fuel sender from Motorworks and replaced that too.
Nada. Nothing.
I get no 4L warning.
Should i try to find an instrument with the 7L + 4L or there is a chance to make this one work?
Thank you

Stan · 2 Re: Fuel Light not working Tue May 15, 2018 3:54 am

Stan

Life time member

Number of posts : 2115

The low fuel sender on the early bikes...to about 1985 is the "stick"on the left side of the tank as you sit on it. The sender unit for the later bikes and also for the instruments with only the one warning light is on the right side of the tank and works in a different way. The later instruments low fuel light will not work on the pre 1985 bikes. Best idea is to use your trip meter to work out how far you can ride safely before you run out of fuel.

George_Pap · 3 Re: Fuel Light not working Tue May 15, 2018 4:10 am

George_Pap

Silver member

Number of posts : 185

Stan wrote:The low fuel sender on the early bikes...to about 1985 is the "stick"on the left side of the tank as you sit on it. The sender unit for the later bikes and also for the instruments with only the one warning light is on the right side of the tank and works in a different way. The later instruments low fuel light will not work on the pre 1985 bikes. Best idea is to use your trip meter to work out how far you can ride safely before you run out of fuel.

This is what i doing Stan for the time. But afte a couple of weeks riding i felt that the fuel consumption is inconsistent based on the tripmeter. Already run out of fuel a couple of times due to this. Sometimes i get 100km out of 6lt of fuel, sometimes i get 80, thats why i feel the need of a warning lamp.
So as i can understand you say that the early fuel sender of my bike is not going to trigger the 4L warning fuel lamp of my newer instrument cluster even that i have already replaced the pcb board with the old one. Correct?

MartinW · 4 Re: Fuel Light not working Tue May 15, 2018 4:33 am

MartinW

Life time member

Number of posts : 3014

Fill up based on your worst fuel consumption which according to you is 80 Km. Fill the bike up after you have done 70 km after the fuel light has come on, or sooner depending on fuel availability. It is not wise to run your bike down to empty. As soon as my fuel light 7 litres left comes on, I will fill up at the next available Service Station. I've never run out in twenty years of owning the bike.
Regards Martin.

George_Pap · 5 Re: Fuel Light not working Tue May 15, 2018 6:52 am

George_Pap

Silver member

Number of posts : 185

MartinW wrote:Fill the bike up after you have done 70 km after the fuel light has come on, or sooner depending on fuel availability.

Problem here is i dont have a working fuel light Martin Sad

Dai · 6 Re: Fuel Light not working Tue May 15, 2018 7:47 am

Dai

Life time member

Number of posts : 5720

As Stan says, your current setup is not going to work. You need an early 4L/7L instrument panel. It's possible to get the later one to work with the earlier sender by modifying the main PCB but having done it, it's fiddly and I'm not sure it's worth the effort. I'm an inveterate fiddler (shame the emoticon is missing... Twisted Evil

)

Rick G · 7 Re: Fuel Light not working Tue May 15, 2018 9:46 am

Rick G

admin

Number of posts : 12058

My fuel gauge is a trip meter and experience. Pushing a bike is a real PITA.

George_Pap · 8 Re: Fuel Light not working Tue May 15, 2018 9:54 am

George_Pap

Silver member

Number of posts : 185

Dai wrote: to get the later one to work with the earlier sender by modifying the main PCB but having done it [smiley]https://2img.net/i/fa/i/smiles/icon_twisted.gif[/smiley] )

Dai swapping the new instrument's PCB with the new instrument's PCB board isn't enough to get it working? Of course some pins of old PCB are on the air since there are no corresponding female plugs on the new one.
Could please let me know of the full modification needed? I m not the most delicate electronic guy but.. maybe worth a try Smile

Sent from Topic'it App

George_Pap · 9 Re: Fuel Light not working Tue May 15, 2018 9:55 am

George_Pap

Silver member

Number of posts : 185

This is the PCB board I swapped.

Sent from Topic'it App

George_Pap · 10 Re: Fuel Light not working Tue May 15, 2018 9:57 am

George_Pap

Silver member

Number of posts : 185

RicK G wrote:My fuel gauge is a trip meter and experience. Pushing a bike is a real PITA.

You bet it is Rick!! I m still trying to estimate my fuel consumption though.
I have even made a thought to carry a spare fuel canister on the rear case until nailing the real l/100km value.

Sent from Topic'it App

Dai · 11 Re: Fuel Light not working Tue May 15, 2018 1:43 pm

Dai

Life time member

Number of posts : 5720

George - I'm very reluctant to start trying to write up the changes I made as it means destroying another main PCB to get the required pins to start modifying the later one back to earlier standards. I happened to have a defective main PCB lying around, so it was a case of nothing to lose.

George_Pap · 12 Re: Fuel Light not working Tue May 15, 2018 1:51 pm

George_Pap

Silver member

Number of posts : 185

I see. But...
Don't forget that I already have a semi destroyed instrument cluster lying around Smile

the one that was on the bike initially .

Sent from Topic'it App

Laitch · 13 Re: Fuel Light not working Tue May 15, 2018 10:51 pm

Laitch

Life time member

Number of posts : 3262

Dai wrote:I'm an inveterate fiddler (shame the emoticon is missing... )

Last edited by Laitch on Wed May 16, 2018 1:43 pm; edited 1 time in total

Stan · 14 Re: Fuel Light not working Wed May 16, 2018 4:07 am

Stan

Life time member

Number of posts : 2115

There is always plan B. A sure way of finding out how much fuel you have is to use a method that costs nothing and every bike, pre 85 and younger is covered. You use a digital fuel gauge......open tank, stick your digit in, feel how much fuel you have, close cap. Do not lick your finger......unless you like it.
drunken

George_Pap · 15 Re: Fuel Light not working Wed May 16, 2018 7:33 am

George_Pap

Silver member

Number of posts : 185

Stan wrote:There is always plan B. A sure way of finding out how much fuel you have is to use a method that costs nothing and every bike, pre 85 and younger is covered. You use a digital fuel gauge......open tank, stick your digit in, feel how much fuel you have, close cap. Do not lick your finger......unless you like it.

The old fashioned way Smile

Dai · 16 Re: Fuel Light not working Wed May 16, 2018 7:43 am

Dai

Life time member

Number of posts : 5720

George_Pap wrote:I see. But...
Don't forget that I already have a semi destroyed instrument cluster lying around the one that was on the bike initially .

Sent from Topic'it App

If the main PCB is still intact, swap that over.

George_Pap · 17 Re: Fuel Light not working Wed May 16, 2018 7:49 am

George_Pap

Silver member

Number of posts : 185

By main PCB you mean the hard plastic PCB board or the blue film cable ?
Or both?

Sent from Topic'it App

Dai · 18 Re: Fuel Light not working Wed May 16, 2018 1:31 pm

Dai

Life time member

Number of posts : 5720

Ignore me - that was a really stupid reply Embarassed

. I should have remembered that your original main PCB is literally toast. I just got an LT instrument panel off ebay because

a. my speedo is playing stupid again
b. it was cheap Smile

So I'll be converting that in the near future. I'll post a 'how-to' but it will come with lots of caveats because it's way to easy to destroy the blue film PCB with the soldering iron.

George_Pap · 19 Re: Fuel Light not working Wed May 16, 2018 1:41 pm

George_Pap

Silver member

Number of posts : 185

Dai wrote: your original main PCB is literally toast.

yup. totally toast it is!
Anyway. i'll keep my eyes on for an early '85 instrument on ebay. Till then i ll keep the lady top refuelled every 100kms to be sure.

Sponsored content

1 Fuel Light not working Tue May 15, 2018 2:44 am

George_Pap

2 Re: Fuel Light not working Tue May 15, 2018 3:54 am

Stan

3 Re: Fuel Light not working Tue May 15, 2018 4:10 am

George_Pap

4 Re: Fuel Light not working Tue May 15, 2018 4:33 am

MartinW

5 Re: Fuel Light not working Tue May 15, 2018 6:52 am

George_Pap

6 Re: Fuel Light not working Tue May 15, 2018 7:47 am

Dai

7 Re: Fuel Light not working Tue May 15, 2018 9:46 am

Rick G

8 Re: Fuel Light not working Tue May 15, 2018 9:54 am

George_Pap

9 Re: Fuel Light not working Tue May 15, 2018 9:55 am

George_Pap

10 Re: Fuel Light not working Tue May 15, 2018 9:57 am

George_Pap

11 Re: Fuel Light not working Tue May 15, 2018 1:43 pm

Dai

12 Re: Fuel Light not working Tue May 15, 2018 1:51 pm

George_Pap

13 Re: Fuel Light not working Tue May 15, 2018 10:51 pm

Laitch

14 Re: Fuel Light not working Wed May 16, 2018 4:07 am

Stan

15 Re: Fuel Light not working Wed May 16, 2018 7:33 am

George_Pap

16 Re: Fuel Light not working Wed May 16, 2018 7:43 am

Dai

17 Re: Fuel Light not working Wed May 16, 2018 7:49 am

George_Pap

18 Re: Fuel Light not working Wed May 16, 2018 1:31 pm

Dai

19 Re: Fuel Light not working Wed May 16, 2018 1:41 pm

George_Pap

20 Re: Fuel Light not working

Sponsored content