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I can't tell by looking at the schematic in the manual.
 

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It appears to be a thermistor, so you should be able to check it with an ohmmeter. The manual is very silent on this device. It cannot set fault codes, and the converted value can not be inspected in diagnostics mode. I'll bet that if it gets too hot, it would shut the pump / Engine down. It also does not show up in any diagnostics charts in the manual.
 

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Fried Okra said:
Is the sensor on the side of the fuel pump a Capacitance sensor or a Thermistor?
Neither ...a thermistor is used to detect temperature which isn't the caseand a capacitance sensor it's not based on the diagram.

I've never seen the Warrior fuel pump removed, but it's well documented in the Yamaha factory manual (YFM) for troubleshooting and can be easily identified in the wiring diagram as 2-components with the 4-plug connector (Item 12).
  • Fuel pump - red/blue & black
  • Fuel sender - green & black
The fuel sender is discussed in the early YFM on 7-52 and is illustrated as a resistor so i would suspect it is a float sensor. It outputs to the Tachometer assy circuit board with a discrete signal which is then delivered to the low level fuel indicator in the speedo IMO.

Fried Okra .... as i recall from an earlier post of yours that i responded to, you have a spare fuel pump .... how about posting a close-up jpeg photo of the assy for us that identifies the float/sensor unit so we can see


Warrior hosted wiring diagram by writer HERE
 

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It's not drawn like a float level indicator, but who says yamaha follows convention. I wouldn't think that a capacitive probe (as used in aviation) would be drawn like that, and they require AC excitation unless the Exc. and Demod are self contained (in which case you probably would not get a reliable resistance measurement due to the electronics involved). Ultrasonics are usually mounted at the top of the tank firing the signal down (again active electronics so no resistance measurement). I could be something simple like a self heated thermistor so that when the fuel uncovers it, the temp rises and sets off the low fuel light. You excite these with a constant current, when the resistance changes (i.e. when fuel uncovers) , the current remains constant, but the voltage required to maintain the constant current changes and can be detected. This is thesimilar effect as used in a mass airflow sensor and since its a Go / No-Go indicator, much simpler than a float. This is just speculation on my part since I have worked on a similar application, I'd have to see it.


BTW forget about the overtemp thing above, I was posting at work, while thinking about an overtemp issue WTF!!!!!
 

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Discussion Starter #6
Ok, ok. It's a Thermistor. I made it work by trial and error, also a lot of research. but check this out, as strange as it may seem it works, but not with an LED, has to be a bulb type.
As Follows:
Tungsten (what bulb filaments are made of) increases in resistance as it gets hot... light bulbs pull most current when they are first switched on and taper off as they light up. I still don't really understand how the thermistors in the tank work, but my guess is this:
1. The bulb allows a small amount of current to flow through the thermistor, which heats it.
2. If the thermistor is submerged in fuel, the heat is dissipated and it remains high resistance.
3. If the fuel drops so the thermistor is in free air it can warm up a bit and so its resistance drops, turning on the light.
4. The resistance of the light increases as it comes on, stabilising the current through the thermistor.

I'll post a diagram of how to wire it when I get home. PS. A Relay don't work.
 

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You got in Fred!!! So its an NTC thermistor (negative temperature coefficient)





You can also do this with RTD's. They are much more accurate, but are very costly. We use them to measure the inlet temperature of jet engines very very accurately.
 

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There must be some way to do it with an LED. That is what lights up the stock low fuel light. I asked "armystar" who has had his speedo apart before. I have no idea howyou woulddo it though.
 

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AlanH said:
Fried Okra .... as i recall from an earlier post of yours that i responded to, you have a spare fuel pump .... how about posting a close-up jpeg photo of the assy for us that identifies the float/sensor unit so we can see
If Fried Okra would be so generous to share a photo as requested above some of us wouldn't be in the dark
... The industrial thermistors that i have worked with for induction heating, etc are shaped like a pancake and easy to identify.
  • I do know for fact that the low fuel indicator light doesn't come on immediately after restarting the bike when parked and on reserve and i've never had the opportunity to evaluate it's operation regarding the light intensity.
I still believe that there is an integrated circuit for the output of the sensor in the Tach head else the wire would run direct to the speedo which is not a filament as stated by Brandon.
 

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Discussion Starter #11
Here is something I found similar to what the warrior has. Works for me.
Our wires from the thermistor to the fuel pump housing connector is Black (ground) White (thermistor), from the fuel pump housing connector the white wire turns into the green wire to the light bulb then on to power supplied by the switch.
 

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Discussion Starter #12
Here is something else for the LED. I haven't tried it but the guy that I found this info from said it works. I will try it next week. The parts needed are: 3V 20 mA LED; LED Holder; 47 ohm 5w ceramic power resistor (load resistor); 470 ohm metal film resistor (current limiting). SEE PICTURE
 

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When you get this thing all wrapped up will you do a really good write up w/ lots of pics for us. I am really interested in this led light. The Dakota Digital guage I want has every function except low fuel. Your research could really help me out.
 

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Fried Okra said:
I hope this picture posts, if not someone tell me how.

Fried Okra thanks for the photo and the submitted info

Not what i expected it to look like

Does the large cylindrical end w/wires face straight up?

BlackStar as usual you've provided some excellent technical info on the subject ..... i wasn't aware that NTC & RTC devices were used for this type application
 
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