Fuel level gauge in tachometer is stuck

[JayH]

I have a tachometer from an 84 GS1100GK that appears to be stuck. The gauge reads a little over 1/2 full and doesn't move. So far I pulled the wires to the sending unit off and get 6 ohm across the wires. Shorting out the leads going to the sending unit doesn't move the gauge.

Today I'm going to try and trace the connection up to the tach but right now it looks like the problem is w/ the gauge in the tach. Has anyone seen this before?

[DMPLATT]

My 750E's gage floated a bit. Wasn't stuck. I found that I had trouble after I removed tank each time. Found it was ok after cleaning the connectors.

I'd say if the ohms check out, may well be a bad gage. Is the fuel gage seperate and can be replaced by itself? Mine is.

I would follow the wires as you intend. Perhaps a broken wire is all it is.

Good Luck, sorry I'm not much help.

[earlfor]

The guage is different on the bike than it is on a car. On a car, turn the ignition off and the fuel guage needle drops to empty and rises again when you turn the ignition back on. On the bike, the guage is designed to retain the last reading and never return to the empty mark. Turn the ignition off on the bike and if you have 1/2 a tank of fuel, the needle will still indicate 1/2 tank. That is how it is supposed to work. If you havent ridden the bike any amount of miles, the needle should never move, ignition on or off, bike running or not, makes no difference.

Earl

I have a tachometer from an 84 GS1100GK that appears to be stuck. The gauge reads a little over 1/2 full and doesn't move. So far I pulled the wires to the sending unit off and get 6 ohm across the wires. Shorting out the leads going to the sending unit doesn't move the gauge.

Today I'm going to try and trace the connection up to the tach but right now it looks like the problem is w/ the gauge in the tach. Has anyone seen this before?

[5RON5]

'79GS750L Fuel gauge/tank float wires?????

Mine has a gauge also. But I think there is a wire to a terminal in the center of the float, under the left side of the tank. And another one just above that one w/a terminal. But my wire terminal is broke off the center terminal, I think! What I would like to know, is there a wire in the center of the float for a wire? I can re-solder one that goes to the electrical, if there is a wire terminal that is there! Can somebody please help me w/any answers to this problem? I am soooo tired of running of of gas! I know there's a lot of bikes out there w/fuel gauges on there bikes, & would know how many wires there are to that float under the tank on the left side. Would somebody please help me? PLEASE! Ron...

[mixongw]

The fuel gauge in these bikes use an electrodynamic or balanced coil type movement. There is no return spring like in a analog voltmeter. The position of the pointer is achieved using a balance or offset of current in two opposing coils in the movement. If the currect in each coil is equal, the meter will read in the center of the range (half tank). There are three connections to the gauge. One is battery positive, one is ground and the other is the sense connection that goes to the sending unit. The sending unit has only two connections, ground and the sense connection. If the tank is full and the float is at to top of the tank, the sense connection will have a potential nearly the same as the battery positive voltage. This will unbalance the coils in the gauge in the positive direction causing the indicator to show a full tank. If the tank is empty and the float is at the bottom of the tank, the sense connection will have a potential nearly the same as ground (zero volts). This will unbalance the coils in the gauge in the negative direction causing the indicator to show empty. The gauge or movement has a built-in historisis or dampening so as not to show the sloshing around of the fuel when going down the road.

[duaneage]

If you can get the tach open you might have a spider living in the mechanism. The home page of the GSR has a link showing how to open the gauges.

[JayH]

Dave,
Unfortunately the gauge is embedded inside of the tachometer and in order to get access to it the shell would have to come apart. :-(

The good news is that I took some time to clean up the connectors, installed a functioning tach w/ embedded fuel gauge off of another bike, hooked it up, and it went from E to F in seconds.

I wan't able to find the specifications on the resistance (in ohms) to the fuel sender on this particular bike for F, 1/2 full, and E BUT noticed that 6 Ohms was close to some other GS1100 specs when the tank is F.

My 750E's gage floated a bit. Wasn't stuck. I found that I had trouble after I removed tank each time. Found it was ok after cleaning the connectors.

I'd say if the ohms check out, may well be a bad gage. Is the fuel gage seperate and can be replaced by itself? Mine is.

I would follow the wires as you intend. Perhaps a broken wire is all it is.

Good Luck, sorry I'm not much help.

[JayH]

Thanks for the info Earl!

I'm hoping that there is a bad connection somewhere in the shell of the tach because I put another tach w/ embedded fuel gauge on the bike and the fuel gauge went from E to F in seconds.

In the initial post I neglected to say that the tank was just filled up. In the Suzuki GS1100 maual it has these following specs for the fuel gauge:

Full - 1 to 5 Ohms
1/2 - 25 to 40 Ohms
Empty - 100 to 120 Ohms

I'll do some more testing later on this p.m.

The guage is different on the bike than it is on a car. On a car, turn the ignition off and the fuel guage needle drops to empty and rises again when you turn the ignition back on. On the bike, the guage is designed to retain the last reading and never return to the empty mark. Turn the ignition off on the bike and if you have 1/2 a tank of fuel, the needle will still indicate 1/2 tank. That is how it is supposed to work. If you havent ridden the bike any amount of miles, the needle should never move, ignition on or off, bike running or not, makes no difference.

Earl

[JayH]

Thanks for the info and diagram mixongw!

I won't be able to get to the bike today to do any more testing but will see if I can dig up some wires, power supply, etc. to do some other testing later on this p.m.

Any movement from the gauge will make me feel better but if it comes down to it I'll open up the tach to get better access to the fuel gauge.

The fuel gauge in these bikes use an electrodynamic or balanced coil type movement. There is no return spring like in a analog voltmeter. The position of the pointer is achieved using a balance or offset of current in two opposing coils in the movement. If the currect in each coil is equal, the meter will read in the center of the range (half tank). There are three connections to the gauge. One is battery positive, one is ground and the other is the sense connection that goes to the sending unit. The sending unit has only two connections, ground and the sense connection. If the tank is full and the float is at to top of the tank, the sense connection will have a potential nearly the same as the battery positive voltage. This will unbalance the coils in the gauge in the positive direction causing the indicator to show a full tank. If the tank is empty and the float is at the bottom of the tank, the sense connection will have a potential nearly the same as ground (zero volts). This will unbalance the coils in the gauge in the negative direction causing the indicator to show empty. The gauge or movement has a built-in historisis or dampening so as not to show the sloshing around of the fuel when going down the road.

[JayH]

I'm hoping my girlfriend doesn't see this post. She hates spiders!!

I'll be more than happy to evict him in order to get the gauge to work.

If you can get the tach open you might have a spider living in the mechanism. The home page of the GSR has a link showing how to open the gauges.