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51Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Tue Apr 29, 2014 4:30 pm

duck


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if your bike didn't come with gauges from the factory then it's probably taped off to the clump of wires and not hanging out in the open.

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52Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Tue Apr 29, 2014 4:47 pm

billtr96sn

billtr96sn
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I think I will give up looking for the special connector and just tap into the wires from the sender and find a switched 12v feed near to where I am going to put the gauge.


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Something witty is supposed to go here... help!! Testing In Tank Fuel Sender Unit - Page 2 Uk-log10
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53Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Fuel gauge Thu Jun 05, 2014 11:15 am

Pento1966

Pento1966
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robmack great read. a bit beyond my ability can i buy a new sender unit? and install it ofr a fix wrote:I had a chance to look at my failing fuel level sender today and discovered information that would be useful for the community.

How does it work:
The sender has a movable arm ending in a float that raises and lowers according to the fuel level.  The arm articulates a pair of metal wipers over two circuit cards.  The assembly is housed in a metal box welded to a bracket that mounts to the bottom of the tank.  The wiring goes through a liquid-tight connector assembly.
Testing In Tank Fuel Sender Unit - Page 2 DSC_0018


Fuel Level Sensing:
The upper wiper sweeps across a 130 ohm wire wound resistor plate, one end of which is connected to the liquid-tight connector and the other end is not connected to anything.  The lower wiper sweeps across another plate containing two circular contacts, one of which is wired to the liquid-tight connector, the other is not connected at all.  The upper wiper outputs a resistance value between 2 and 130 ohms, proportional to the position of the wiper.

When the tank is full of fuel, the float is in its highest position and the resistance measured should be around 2 ohms. When the tank is nearly empty, the float is at its lowest position and the resistance measured should be around 130 ohms. 

To test the resistive wire, use a multimeter with resistance measuring capability.  As in the photo set below, when measuring between the connector and the left side of the resistor, the value should be around 130 ohms.  
Testing In Tank Fuel Sender Unit - Page 2 DSC_0024Testing In Tank Fuel Sender Unit - Page 2 DSC_0032

When measuring between the connector and right side of the resistor, the value should be around 2 ohms.
Testing In Tank Fuel Sender Unit - Page 2 DSC_0025Testing In Tank Fuel Sender Unit - Page 2 DSC_0030

Reserve level Sensing:
The lower wiper outputs a binary signal -- open circuit or grounded -- that communicates the reserve volume to the low fuel light on the instrument cluster.  Normally, when the tank is full of fuel, the circuit is open.  When the arm reaches a certain position, the wiper contacts the conductor and the output gets grounded.  This signals when the float reached the reserve position and the instrument light should illuminate.

To test, , use a multimeter with resistance measuring capability.  As in the photo set below, there should be conductivity between the connector and the left side plate.  
Testing In Tank Fuel Sender Unit - Page 2 DSC_0026

There should be no conductivity between that same conductor and the right side plate.
Testing In Tank Fuel Sender Unit - Page 2 DSC_0027

How to Recondition the Sender:
The sender tends to fail because years of accumulated corrosion prevents conductivity. The symptom of corrosion will be erratic resistance readings from the upper wiper.  In the photo below, note the thick brown corrosion on the pivot hole and green corrosion on the float arm pivot.  All this corrosion prevents an accurate resistance measure being sent to the fuel gauge. To recondition a failing sender, it is necessary to open the metal box and clean the contacts.  

There are four tabs that hold the case closed.  Carefully bend the tabs straight and the top will separate.  Be careful because there is a spring under the wiper arm and it may fly off. 
Testing In Tank Fuel Sender Unit - Page 2 DSC_0021

Remove the wiper arm and check that the contact pads look clean and shiny.  
Testing In Tank Fuel Sender Unit - Page 2 DSC_0023

Depending on the age of the sender and other factors, it may take no more than some Deoxit cleaner and a cotton swab to clean the corrosion from the wires.  I would try this first.  If the Deoxit doesn't get rid of the accumulated corrosion, resort to a mildly abrasive paper.  Using a small piece of 1200 grit wet and dry sandpaper, carefully clean the resistive wires of accumulated corrosion.  The technique is to fold a tiny piece in half so that is has some stiffness and careful drag it across the wires IN THE SAME DIRECTION AS THE WIRES ARE WOUND.  I use emphasis because you don't want to drag the abrasive paper across the wires as it may break them.  Don't use any more pressure than is offered by the stiffness of the sandpaper, such as pressing with your finger.  The wire used is very brittle and can easily break.

Using the same 1200 grit wet and dry, clean in and around both pivot holes as well as the float arm pivots.  It is important to clean all corrosion from the pivots as from the hub where the wiper blades are fixed.  The spring is there to act as a conductor, to allow electricity to flow through the wipers, through the spring, through the pivots to ground.  This is the critical area where corrosion buildup will break the sender.  Once all corrosion is removed, reassemble the parts.  
Testing In Tank Fuel Sender Unit - Page 2 DSC_0034

Test whether the cleaning is successful by measuring the resistance over the entire sweep of the float arm.  The ohm meter should read consistent increasing resistance as the arm moves from full limit to empty limit.

Reserve Level Adjusting
The point where the low fuel light illuminates is dependent on the point during the rotation of the lower wiper when it encounters  the contact plate.  There is an adjustment on the sender which can determine when the lower wiper contacts the plate.

Testing In Tank Fuel Sender Unit - Page 2 DSC_0035

In the photo above, you can see a toothed wheel.  This wheel rotates on a nylon pivot, causing the bottom plate to be rotated and the contact to change position.  Using a small screwdriver, get a purchase on either of the indicated lever points and engage the tip of the screwdriver's blade with one of the teeth of the wheel.  Rotate the wheel with a levering action.  


  • Rotating the wheel CLOCKWISE will cause the wiper to contact earlier, resulting in a LARGER reserve volume. 
  • Rotating the wheel COUNTERCLOCKWISE will cause the wiper to contact later, resulting in a SMALLER reserve volume.

    

54Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Jun 05, 2014 2:03 pm

robmack

robmack
Life time member
Life time member
You can always buy a new or slightly used sender unit to replace a broken one.  I don't have any myself for sale.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

55Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Wed Dec 24, 2014 2:25 pm

Mark K Boy

Mark K Boy
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@robmack wrote:You should tap off the Additional Instruments connector  for your automotive fuel gauge.  This connector provides all the signals you'll need for your gauge -- ground, +12V, sender and parking lights.  I don't know your type of gauge, but normally one side of the gauge is to +12V and the other to the sender.

Be aware that the BMW sender works opposite to modern fuel senders.  Your gauge may respond falsely, indicating empty when the tank is full.  Hopefully it can be adjusted to compensate.
Hi Rob,

I have the above last sentence going on with a VDO fuel gauge, it reads empty when the tank is full,
is there a solution for this?


__________________________________________________
Mark Surman
Keep the shinny side up !

Testing In Tank Fuel Sender Unit - Page 2 Au-log12
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56Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Wed Dec 24, 2014 7:59 pm

RicK G

RicK G
admin
admin
I recall Robmac making a post about that very thing but can't find it. Basicly the gauge sender is a wire pot and if you reverse it i.e. earth side to the gauge and gauge side to earth it comes up a winner but I am not sure if that was all that was done.
You will need to remove the sender mechanism from the tank or at least don't use a butane soldering iron inside the tank because Careflight doesn't do rescues from the upper ionosphere as yet.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

57Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Wed Dec 24, 2014 11:10 pm

charlie99

charlie99
VIP
VIP
marky  test to see of it shows something if the fuel sender is dunked towards the bottom of a fullish tank ?


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTesting In Tank Fuel Sender Unit - Page 2 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

58Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 4:25 am

Mark K Boy

Mark K Boy
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Gold member
Thanks guys,
I tried swapping the wires. No joy.
I'm sure when I took it for its first road test that the gauge read 1/2 = 1/2 full right?  But when I filled her up, she went to empty. no problem I thought, swap the wires...  
Any how,,,  good idea Charlie, then we will have the truth.
Ofcourse I could just turn the gauge up side down..... Don't laugh..   
Gentlemen, stand down please, after all it is Christmas day!!!

Have a good one.


__________________________________________________
Mark Surman
Keep the shinny side up !

Testing In Tank Fuel Sender Unit - Page 2 Au-log12
http://www.marksurman.com
    

59Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 5:01 am

charlie99

charlie99
VIP
VIP
swapped the wires ..please explain ?

you would need to change the ends where the cables  attaches to the resistor  thingy on the sender  so that the resistance change is in the opposite direction whilst still maintaining the same physical action .?   or that what makes sense to me


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTesting In Tank Fuel Sender Unit - Page 2 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

60Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 6:23 am

billtr96sn

billtr96sn
Silver member
Silver member
I had the same problem using a VDO gauge from a car, in the end it was easier and cheaper to use the correct gauge. Very easy after that.


__________________________________________________
Something witty is supposed to go here... help!! Testing In Tank Fuel Sender Unit - Page 2 Uk-log10
http://www.billsbikechat.co.uk
    

61Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 6:58 am

Mark K Boy

Mark K Boy
Gold member
Gold member
Charlie, I swapped the wires at the back of the gauge. This did not work as stated, it just sends the needle to extreme full, the same position if the tank connector is not connected and bike is turned on.

You have a higher reality of the inner workings of these things than I - Your solution makes sense to me - battery on charge overnight, I shall dunk the sender in the morning to establish that I do have a reversal issue.

If so, I will then be giving myself a higher reality of the inner workings of these things....

Bill, I hear ya,,,,,,,  But ,,,,,,

Testing In Tank Fuel Sender Unit - Page 2 7beef37015ddb68d4bf696bdfb2e4f40  Testing In Tank Fuel Sender Unit - Page 2 3b5f83a5439bb7d451a1f3f9199fa515

They are just so pretty !


__________________________________________________
Mark Surman
Keep the shinny side up !

Testing In Tank Fuel Sender Unit - Page 2 Au-log12
http://www.marksurman.com
    

62Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 1:20 pm

robmack

robmack
Life time member
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Swapping the wires at the back of the gauge will not solve the problem.  The wire-wound resistor card on the fuel sender needs to be flipped so that the reverse side of the resistor is being used.  This reverses the "full tank" - "empty tank" values, making it compatible with modern gauges.  This operation requires that the sender be removed from the tank and completely disassembled/reassembled.  I read one posting by one person on Motobrick who claimed that this was possible.  I have a spare sender at home and I'm going to try out and document this operation.  I'll post my findings to this thread.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

63Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 5:32 pm

charlie99

charlie99
VIP
VIP
nice rob ...good to have a spare to play with ...

cheers


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTesting In Tank Fuel Sender Unit - Page 2 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

64Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 7:24 pm

Mark K Boy

Mark K Boy
Gold member
Gold member
Thanks Rob,
I was dreaming, I put in a oil pressure gauge at the same time and upon 1st starting the bike I had to reverse the inputs to the back of the pressure gauge , no problem....
To do the same in the hope that the fuel gauge would work properly was not correct, and embarrassing, as I do know better.    Embarassed

Charlie, I will dunk the sender soon.

I have to do some work on my ALT after that so Ive got something to go with.


__________________________________________________
Mark Surman
Keep the shinny side up !

Testing In Tank Fuel Sender Unit - Page 2 Au-log12
http://www.marksurman.com
    

65Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Thu Dec 25, 2014 10:14 pm

Mark K Boy

Mark K Boy
Gold member
Gold member
Charlie and others,

Happy to report that the gauge does work in reverse to its full range smoothly.

Rob said he was going to get he hands dirty.
I will wait awhile as I have other problems to solve. Failing that, I'm better with the physical rather than the theory.

Thanks.



Last edited by Marky Boy OZ on Fri Dec 26, 2014 6:19 am; edited 1 time in total


__________________________________________________
Mark Surman
Keep the shinny side up !

Testing In Tank Fuel Sender Unit - Page 2 Au-log12
http://www.marksurman.com
    

66Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Fri Dec 26, 2014 3:19 am

charlie99

charlie99
VIP
VIP
good to hear !!


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTesting In Tank Fuel Sender Unit - Page 2 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

67Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Sun Dec 28, 2014 9:12 pm

robmack

robmack
Life time member
Life time member
Marky Boy OZ wrote:Rob said he was going to get he hands dirty.
I will wait awhile as I have other problems to solve. Failing that, I'm better with the physical rather than the theory.

Thanks.
I did the proof of concept swap with the fuel sender board and documented the process in a new How-to post:

Messing with the In-tank Fuel Sender


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

68Back to top Go down   Testing In Tank Fuel Sender Unit - Page 2 Empty Re: Testing In Tank Fuel Sender Unit Sun Dec 28, 2014 9:35 pm

Mark K Boy

Mark K Boy
Gold member
Gold member
Thanks Rob,

Great timing


__________________________________________________
Mark Surman
Keep the shinny side up !

Testing In Tank Fuel Sender Unit - Page 2 Au-log12
http://www.marksurman.com
    

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