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Discussion Starter #1
Instead of running the instrument cluster I'm running a XT Racing GPX Pro.

I wired up a nuetral and oil pressure light but I'm having problems with the fuel light.

Anyone know how the sensor/switch works? The housing is grounded and it has a signal wire. The resistance doesn't change w/ or w/o fuel and its not an open/close switch.

Any ideas?
 

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pg 16-73 in the oem service manual?
 

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Discussion Starter #4
The only thing the manual says is how to test it for being bad. Now, you'd think you might be able to interpret that information to determine the type of signal. But I haven't been able to.

The book says fill the tank, ground the ground wire and then check the signal wire with a test light that is hooked to a battery. If it turns on the sensor is bad.

So you'd think the test light would illuminate when there is no fuel in it, right? Wrong.
 

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The only thing the manual says is how to test it for being bad. Now, you'd think you might be able to interpret that information to determine the type of signal. But I haven't been able to.

The book says fill the tank, ground the ground wire and then check the signal wire with a test light that is hooked to a battery. If it turns on the sensor is bad.

So you'd think the test light would illuminate when there is no fuel in it, right? Wrong.
Every fuel sensor I know of used in automotive applications uses a float, that is tied to a resistor. The change in resistance equals the level of fuel in the tank.

I don't know if the resistance goes from high to low, or low to high over the range of Empty to Full.

If you have the assembly out of the tank, it wouldn't be hard to sort it out.

With it in the tank, it should still not be terribly difficult.

Put your meter in Ohms, and place the black lead on the ground point used by the tank. Put the red lead on the sense line from the float. Read the meter.

Change the amount of fuel in the tank, so the float moves and repeat the measurement. Best to go to the opposite extreme so you can see the maximum change.

Let us know if that gets you anywhere.
 

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Discussion Starter #6 (Edited)
Every fuel sensor I know of used in automotive applications uses a float, that is tied to a resistor. The change in resistance equals the level of fuel in the tank.

I don't know if the resistance goes from high to low, or low to high over the range of Empty to Full.

If you have the assembly out of the tank, it wouldn't be hard to sort it out.

With it in the tank, it should still not be terribly difficult.

Put your meter in Ohms, and place the black lead on the ground point used by the tank. Put the red lead on the sense line from the float. Read the meter.

Change the amount of fuel in the tank, so the float moves and repeat the measurement. Best to go to the opposite extreme so you can see the maximum change.

Let us know if that gets you anywhere.
The ZX6R doesn't have a float in the way you are thinking. Most systems like this would typically use a ball float switch. When the fuel gets below a certain level the ball drops and completes or breaks a circuit. I assume Kawi decided against a system like this due to fuel slosh.

Either way, I already did a resistance test like i stated in the original post.

I've already done all the conventional checks. I am starting to think its a digital signal.
 

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The ZX6R doesn't have a float in the way you are thinking. Most systems like this would typically use a ball float switch. When the fuel gets below a certain level the ball drops and completes or breaks a circuit. I assume Kawi decided against a system like this due to fuel slosh.

Either way, I already did a resistance test like i stated in the original post.

I've already done all the conventional checks. I am starting to think its a digital signal.
I have to agree, the circuit has to be a very simple one -- my tank is only telling me when it gets below a certain point and the low fuel light comes on.

What two points were you making your resistance measurement between? As they say in the manual that it's a failure when you read a short, I have to presume that's what it should read when the tank is empty. Wouldn't want the customer to be told the tank is empty when it isn't...

I'd guess an open would indicate some condition other than empty.
 

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Discussion Starter #10
I have to agree, the circuit has to be a very simple one -- my tank is only telling me when it gets below a certain point and the low fuel light comes on.

What two points were you making your resistance measurement between? As they say in the manual that it's a failure when you read a short, I have to presume that's what it should read when the tank is empty. Wouldn't want the customer to be told the tank is empty when it isn't...

I'd guess an open would indicate some condition other than empty.
I checked between signal and ground, I also checked with a light hooked in and 12v supplied on one end of the light with my meter inline.



If an open circuit indicates something other than empty, you'd assume a closed circuit would indicate empty.

But it really has neither. It always has a high resistance 1.867-1.4 kohm to ground regardless of fuel level.
 

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I checked between signal and ground, I also checked with a light hooked in and 12v supplied on one end of the light with my meter inline.



If an open circuit indicates something other than empty, you'd assume a closed circuit would indicate empty.

But it really has neither. It always has a high resistance 1.867-1.4 kohm to ground regardless of fuel level.
There's high resistance, and then there's high resistance. An open circuit would read in millions of Ohms.

I don't think the sensor in the tank should ever be given any significant current.... can you say sparks?

1,400 Ohms/12 Volts means the current applied in the tank would never be higher than about 0.01 Amperes -- low enough that you couldn't ignite the fuel. A dead short would allow as much juice as the system could provide, which would surely be enough to get something hot enough to be a problem.

If you measured a range of resistance between 1,867, and 1,400 Ohms, that would indicate a 467 Ohm range. Plenty to show full or not, without ever allowing a possible source of ignition.
 

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Maybe looking at it from the other side would be helpful. What can the GPX Pro interpret and use as a fuel lvl signal?

Just from reading the service manual, I'm under the impression that you should always see some resistance between the signal wire and ground. One thing you could try would be to empty the tank, hook up your ohm meter to it and start filling it. See if you get to a point where there is a significant change in the resistance. (by significant I mean that 400 ohm difference you mentioned) That point where the low fuel lvl light would go out. If there is then the ECU or meters on the bike are just referencing two resistance values. One for low and one for not low fuel. Just a guess though since I don't have the inclination to take my bike apart and try and figure it out.
 

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Discussion Starter #14
Maybe looking at it from the other side would be helpful. What can the GPX Pro interpret and use as a fuel lvl signal?

Just from reading the service manual, I'm under the impression that you should always see some resistance between the signal wire and ground. One thing you could try would be to empty the tank, hook up your ohm meter to it and start filling it. See if you get to a point where there is a significant change in the resistance. (by significant I mean that 400 ohm difference you mentioned) That point where the low fuel lvl light would go out. If there is then the ECU or meters on the bike are just referencing two resistance values. One for low and one for not low fuel. Just a guess though since I don't have the inclination to take my bike apart and try and figure it out.
The GPX doesn't have any fuel level capability.

I have already done what you suggested and there isn't a variance that is consistent.
 

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Some this is purely an academic question about how it works? Not a practical question of using it with a different gauge cluster.
 
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