wiring problem with fuel gauge

[rscbao]

One thread stated that if the needle on the fuel gauge remains past full, that it is caused by a "dead short to the ground wire." Having tested the fuel gauge needle and found that it works, I am assuming that this is the problem with the fuel gauage on my 82 GS1100GL. Could someone tell me the process to correct the short? (It is the little problems which tend to take more time and cost more money, isn't it?)

 

[duaneage]

Start with unhooking the ground wire from the sending unit in the tank. If it is still stuck there is a short to ground somewhere. Unhook the other wire and see if it goes down. If not, the short is in the wiring between the tank and the gauge. Good lick with that.
If unhooking the wires on the sending unit allows the gauge to go down, drain the tank and repair or replace the sending unit.

Mine has an opposite problem. My gauge drops to empty and then goes back up every now and then, but that's a winter project since i need to drain the tank and clean the sending unit

 

[rscbao]

fuel gauge wiring problem continued

fuel gauge wiring problem continued

Dear Sir:

Thank you for your response. I have found that the original sending unit does not work from testing it. However after trying one that does work, I have found that the gauge needle still does not move. I then took the gauge by a shop where it was tested before my eyes showing that the needle component was good. In addition there is continuity on both wires, y/b and b/w, from the gauge end of the wires to the female end into which the sending unit hooks.

Now the wires go into the headlight and from the headlight to the gauge. There is a four pen hookup. When testing the y/b wire, which is no longer hooked to the gauge, no current measurement was found. If it is not hooked to the gauge, will current not be detected or is there another problem with the hot y/b wire?

Also I tested the g/o wire connecting to the gauge and it showed 11 volts on the voltmeter, so it is receiving current.

Look forward to your further suggestions.

 

[duaneage]

11 volts sounds low, I would put a battery trickle charger on the bike to help the battery out when testing, you should have at least 12.5 on it with the key on.
Access the back of the gauge oin the dash and try these tests.

On the gauge in mine I have an orange wire with 12.5 volts on it. I also have a ground , this is the reference ground. After measuring the +12, switch to ohms and measure the ground connection on the back of the gauge to the bolt next to the horn, this is usually where Suxuki grounds the stuff in front. If the ground connection , black with white stripe) is not 0 ohms or close to it then fix that temporarily with a length of wire from the ground to the gauge ground and retest.

After we have determined the gauge is grounded adn powered up temporarily run a length of wire from the third connection to the gauge, bypassing the yellow/black wire, and see if that resolves it. If the gauge is out of the tank this gets easier, since you can vary the reading by hand.

This is a pain in the ass to troubleshoot but it is a simple problem. The gauge is a volt meter and the sending unit is a variable resistance. Both are referenced to the ground of the bike. It might just be the grounds are bad, a common problem in Suzukis.

 

[rscbao]

Testing gd & g/o wire

Testing gd & g/o wire

Dear Sir:

There is no black and white ground wire to a bolt next to the horn. So per your instructions I need to run a wire as a ground from the back of the gauge needle element to the frame next to the horn, and then start the testing. There are two black wires which hook on the horn, one of which should be a ground wire. From a wire diagram I have it seems that one of the wires must run to the horn button (dg=dead ground?) and one to the kick stand ground wire.

In addition the two black wires connecting into the horn run backwards into the harness and from there it is not clear where they go.

Does it matter how the wires are placed on the horn?

Also the diagram I have shows horns and not just one horn are these 82 1100GLs suppose to have more than one horn?

After writing the above, I conducted the tests you recommended. I connected a ground from the fuel gauge and placed it next to the horn on the frame and extended a wire from the y/b connector on the fuel gauge to the fuel sending unit while connecting the latter into the existing b/w female connector. The gauge went from full to empty over a five to ten minute period. However it would not go from empty to full. In addition, even with the battery charged to full I was unable to get a reading above 11 on the orange wire.

Testing the old b/y wire in ohms registers a .4 and the b/w registers .7 (wires running from sending unit to head light with key off). The new y/b by-pass wire registers .2 where it is attached to the back of the fuel gauge and .1 at the other end where the sending unit would hook to it on DC at a setting of 200 with key on. Should the latter be higher?


Do you have further suggestions? This thing is about to whip me. One other bit of information which might or might not be relevant is that the front turn signals have been wired in such a way that they remain on along with the front light. I do not know if this might have some bearing on the fuel gauge.


Sincerely,

Richard

 

[tfb]

Mine has an opposite problem. My gauge drops to empty and then goes back up every now and then, but that's a winter project since i need to drain the tank and clean the sending unit

Probably an intermittent connection between gauge and sender unit. Try the bullet-connectors underneath the tank.

 

[rscbao]

inconsistent needle

inconsistent needle

It sounds like you have a short that doesn't always short. I actually drained the tank to clean it. Then reparied the sending unit by putting new connectors on it--after I had purchased two other used sending units which also work.

However, the problem still remain that the needles will not move when the sending unit moves.

Sincerely,

Richard

 

[duaneage]

Probably an intermittent connection between gauge and sender unit. Try the bullet-connectors underneath the tank.

Did that already. The commnections are good, it's definately inside the sender, just a PITA to take it down, fix it, and reinstall without having fuel leaks. I'm not thrilled to be messing with that seal, as soon as you start messing with things they leak.

 

[rustybronco]

The gauge is a volt meter and the sending unit is a variable resistance. Both are referenced to the ground of the bike. It might just be the grounds are bad, a common problem in Suzukis.

is not the fuel gauge an ammeter?

 

[rscbao]

I attached a by-pass wire to the y/b hook-up on the fuel gauge and it registered .2 volts on dc at the gauage and .1 on the female end. Should the voltage be higher or is that normal?

 

[rscbao]

wiring?

wiring?

Did that already. The commnections are good, it's definately inside the sender, just a PITA to take it down, fix it, and reinstall without having fuel leaks. I'm not thrilled to be messing with that seal, as soon as you start messing with things they leak.

I have three good sending units that have been tested; it seems that it must be in the wiring. Did you see the results of the ohms and voltage tests above?

Richard

 

[J_C]

Mine had the same problem as Duanage's. Turned out there wasn't a float on the wand anymore! I harvested one from another fuel sending unit at the salvage shop and everything works great

On this one, the clymer's actually does a great job of helping to troubleshoot the situation. It was right on. There's also a post somewhere (by Brian I think?) about diassembling the sending unit and ensuring that the lever is lined up with the coil correctly.

That makes me wonder.... Perhaps it always shows full because the screw has come lose in the sending unit and the float wand is no longer moving the lever along the coil. Then the resistance would always read the same (in this case, full). Maybe some of the previous posts could discount this, but my eyes started glazing over when all the electical stuff got posted so I skipped them

 

[rscbao]

Still need help solving this problem on my 82 GS1100GL

Still need help solving this problem on my 82 GS1100GL

Below is where I am in a holding pattern:

Testing the old b/y wire in ohms registers a .4 and the b/w registers .7 (wires running from sending unit to head light with key off). The new y/b by-pass wire registers .2 where it is attached to the back of the fuel gauge and .1 at the other end where the sending unit would hook to it on DC at a setting of 200 with key on. Should the latter be higher?

I have three tested and working sending units; the needle element in the gauge has been tested and works. However, whether I connect the sending unit to the original y/b and b/w connections coming from the harness or the by pass y/b and original b/w the needle gauge remains on empty. This is a change however from where it remained only on full.

Are there any other suggestions that someone might have to help me solve this mystery. (Why is it that the smallest things are always the most difficult solve?)

Sncerely,

Richard

P.S. Thank you for your input and helpful suggestions up to this point!

 

[J_C]

Sorry for the dumb question, but the ignition is on right? The gauge will remain where it is regardless of level until it's powered.


I know extremely little about electrical stuff, so I'm not much help. When you move the wand up and down, you should see a difference in the resistance readings in the sending unit. You did see that right? I'm not sure how you verified that they were working. Because It's either three things.... Its the gauge, it's the Sender, or it's the wiring between the two Likewise for the gauge, that can be tested by shorting the wires with a paperclip. That made mine rise to full, and when I removed it, it fell to empty

 

[rscbao]

Sorry for the dumb question, but the ignition is on right? The gauge will remain where it is regardless of level until it's powered.

Yes, I have been operating it with the ignition on.

I know extremely little about electrical stuff, so I'm not much help. When you move the wand up and down, you should see a difference in the resistance readings in the sending unit. You did see that right?

Yes, I did see this occur with all three sending units.

I'm not sure how you verified that they were working. Because It's either three things.... Its the gauge, it's the Sender, or it's the wiring between the two Likewise for the gauge, that can be tested by shorting the wires with a paperclip. That made mine rise to full, and when I removed it, it fell to empty

I am thinking that it is the y/b wire to the gauge connector, or the screw coming out of the gauge onto which the y/b wire hooks is not responding correctly. Nevertheless, I will try your shorting trick. Thanks!

 

[rscbao]

Present State of Affairs

Present State of Affairs

After hooking everything back up, with a supposedly good sending unit, good gauge, and new by-pass y/b and b/w wires as well as connectors (posi locks), the fuel gauge is now stuck between the red and white areas. There is no movement at all. Do any of you hard-core, do-it-until-it-works, types have any further suggestions.

I would sure like this thing to work before I quit.:-D :-D :-D

 

[tfb]

OK, it's time we asked, what sort of mechanism are we talking about inside the fuel gauge?

If it's anything like the temp. gauge in my old GS1000S, that was a bimetallic strip with a heating coil wrapped arount it.

Do our fuel gauges operate on the same principle? If so, then maybe there's something up with the coil around the bimetallic strip?

Whatever, it still sounds like a right-proper mystery... but I'm trying to come up with a fresh angle that may help yield a solution -- even incidentally! :?

 

[Pharkmeh]

my fuel gauge is called an odometer....:shock:

200km's - better fill it or walk it...

 

[Metal Jim]

Fuel level indicator

Fuel level indicator

The bike is equipped with an alternate fuel level indicator: the petcock.

 

[rustybronco]

OK, it's time we asked, what sort of mechanism are we talking about inside the fuel gauge

it's an ammeter it measures current flow

If it's anything like the temp. gauge in my old GS1000S, that was a bimetallic strip with a heating coil wrapped arount it.?

Do our fuel gauges operate on the same principle? If so, then maybe there's something up with the coil around the bimetallic strip?

i have never taken a fuel gauge apart on a motorcycle but i suspect its just like the temp gauge you described.

How it's wired...
Voltage from the battery is applied to the fuel gauge (E-F gauge) it then goes to the sender (float unit in tank) which is a variable resistor, low resistance=high current flow, high resistance=low current flow, to complete the circuit you must have a return circuit back to the battery (wires, frame ect.) or there is no way current will flow, the more current flow (less resistance) the indicator will move in one direction less current (more resistance) the opposite direction. as you look at it a very simple circuit.
p.s. the temp SENDER (used with a temp gauge) you described was a variable resistor also.