[misko]

Could use a little help from those that have an aftermarket or custom fuel lights working on your bike. I am using a regular flashlight bulb (14V, 240mA), not an LED, and did the wiring according these instructions in the FAQ:

Here's the wires used for the fuel lights. Black with white stripe is ground and connects to both bulbs. The first fuel light hooks to the red with black stripe wire, and the secund light hooks to the black with light green striped wire.

...but nothing worked . Then I looked at the wiring diagram and noticed that with these instructions both sides would be grounded ('cause the fuel sensor is grounded as well), so I used a power line on the light bulb side, but that's not getting me anywhere either. Am I missing something here?

Any ideas?

 

[Syscrush]

You need to make a really simple circuit. Details are in this thread.

 

[Marc]

People seem to have trouble getting their custom fuel lights to work. That is because there is a circuit board in the tach to turn the oem light on and flash it. But according to the service manual, to test the fuel sensors you can use a bulb like you have (3 watt). Run a new separate positive (+)wire to one side of your bulb. Connect the black/white wire from the fuel sensor to negitive or ground it. Then use either the red/black or the black/light green from the sensor to the other side of the bulb (depending how much fuel you want to be left when the light comes on). You're supplying (+) to the bulb and the sensor is going to supply the (-). The manual also mentions having a 10 amp fuse on the positive wire so use a fused circut from the bike. Good luck and maybe do that outside and have a fire extinguisher handy. ;D

 

[misko]

Marc, I thought it should be that simple as well ...I took the bike wiring out of the loop and tested the fuel sensor alone with light bulb and am still getting nothing. Maybe my sensor is bad.

 

[serenade]

People seem to have trouble getting their custom fuel lights to work. That is because there is a circuit board in the tach to turn the oem light on and flash it. But according to the service manual, to test the fuel sensors you can use a bulb like you have (3 watt). Run a new separate positive (+)wire to one side of your bulb. Connect the black/white wire from the fuel sensor to negitive or ground it. Then use either the red/black or the black/light green from the sensor to the other side of the bulb (depending how much fuel you want to be left when the light comes on). You're supplying (+) to the bulb and the sensor is going to supply the (-). The manual also mentions having a 10 amp fuse on the positive wire so use a fused circut from the bike. Good luck and maybe do that outside and have a fire extinguisher handy. ;D

Just to clarify,

Or do you put the Black/ Green on the positive side. I ask because if you ground the light to a constant ground, wouldn't the Black/ Green wire not do anything to the light if it were to come on or pulse or whatever it does?

 

[Marc]

serenade, no, use your pic but unlook the black/white wire from the bulb and ground it. The black/ green wire will ground the bulb when the sensor gets dry.

misko, I've never done this mod, I'm just reading the service manual on how to test the sensors. Syscrush makes a super dash panel in his write up but is using LED bulbs and resistors instead of flashlight bulbs. The manual says it takes a bit for the lights to come on or go off. Make sure you're using a 3 watt (220-240ma) 12-14 volt bulb.

 

[serenade]

Isn't the Black/ White wire a ground already? So do I ground it again, or leave it alone?

 

[Marc]

Isn't the Black/ White wire a ground already? So do I ground it again, or leave it alone?

If you have the plug, under the gas tank, hooked up to the sensor then yes it is grounded already. Sorry about that.

 

[Syscrush]

I'm sorry, I thought you wanted to use an LED. If you want to use a 3W flashlight bulb, then start by just following the instructions in the manual. Does your stock fuel light work?

 

[serenade]

Mine does with the OEM gauges, but now that they are gone, and I made a fuel light, it wont. I have a flash bulb hooked up black/white (-) and red/ black (+). So do I hook up a 12v (+) to one end and the red// black to the other end?

 

[Marc]

So do I hook up a 12v (+) to one end and the red// black to the other end?

If you're talking about the light bulb, then yes. You can get the 12v (+) from the red wire in that plug that went to the gauges. That's where you are accessing the red/black wire, from the plug that went to the gauges, right?
Review, original wire harness still on bike, fuel sensor plugged in under tank, original gauges removed from bike, take plug on wire harness that went to the gauges and connect the flashlight bulb to the red wire and the red/black wire.

 

[serenade]

Awesome. I will try this and let you know if it works. With the gauges on, when you turn on the bike, does the fuel light come on and then go off?

 

[Marc]

Awesome. I will try this and let you know if it works. With the gauges on, when you turn on the bike, does the fuel light come on and then go off?

Yes, but you're taking the gauges off, aren't you? You better be after all the questions.;D

 

[serenade]

The gauges have been off for like 3 weeks. My Vapor gauges ship out tomorrow.

 

[Syscrush]

Mine does with the OEM gauges, but now that they are gone, and I made a fuel light, it wont. I have a flash bulb hooked up black/white (-) and red/ black (+). So do I hook up a 12v (+) to one end and the red// black to the other end?

What you need to have is a 3W bulb in series with the thermistor. The bulb will allow enough current to flow to heat up the thermistor, which results in the resistance dropping, and the current flow increasing to the point where the bulb comes on. If you dunk it into gasoline, that will dissipate the heat which keeps the resistance high and prevents the bulb from lighting.

If the OEM gauge/light works, then the thermistor is good. What you want is power to one terminal of the bulb, then from the other terminal of the bulb to a terminal on the sending unit, then from the other terminal of the sending unit to ground. It should light in about 3-5 seconds.