question on hooking up my fuel sending unit

[eddie0225]

I've never had my fuel sending unit hooked upand was looking into it when I seen it could be dangerous to hook up a 6 volt sending unit to a 12 volt system
My tractor has been converted to a 12 volt instead of 6 so how would I go about hooking it u safely

 

[JMOR]

(quoted from post at 10:25:26 03/13/23) I've never had my fuel sending unit hooked upand was looking into it when I seen it could be dangerous to hook up a 6 volt sending unit to a 12 volt system
My tractor has been converted to a 12 volt instead of 6 so how would I go about hooking it u safely

n an 841, the fuel gauge is nothing more than a variable resistor controlled by a float and a meter to read the current. No regulator involved as in some later tractors. So, I do not believe a direct hook up is going to work. Never done this, but would expect that you need a regulated 6v source, but will let someone with the exact experience explain how to.

 

[Destroked 450]

Haven t looked to see if the part numbers are different but the diesel models were 12 volt negative ground,

 

[Sean in PA]

I would think that you need a new sender and gauge that are matched to each other and are designed for use in a 12 volt system.

 

[JMOR]

(quoted from post at 11:40:25 03/13/23)
Haven t looked to see if the part numbers are different but the diesel models were 12 volt negative ground,

hat sounds like the right solution.

 

[wore out]

LOTS of convertors available to the old car crowd, no reason it won't work on your tractor.

https://www.speedwaymotors.com/Speedway-Runtz-12-Volt-to-6-Volt-Voltage-Reducer,2374.html

ONE source.

 

[JMOR]

(quoted from post at 12:35:20 03/13/23)
LOTS of convertors available to the old car crowd, no reason it won't work on your tractor.

https://www.speedwaymotors.com/Speedway-Runtz-12-Volt-to-6-Volt-Voltage-Reducer,2374.html

ONE source.

as to cost less than diesel sender & gauge, too.

 

[sotxbill]

The sending unit is no more than a variable resister. IT does not care about the voltage. However.. if the guage and sending unit dont match correctly, then the gauge will not read correct. It could read stuck to the top or read empty all the time if the resistance range does not match the gauge. So its not dangerous, but may not function correctly. Dangerous.... if you make a spark while connecting any wire and there are gas fumes around, anything could be dangerous, so it best if you connect it with the key off... again,for any wire anywhere around the tractor and gas fumes.

I would hook up the gauge and try it and see how it works. The full is not important, but the empty is very important.

 

[wore out]

(quoted from post at 14:48:14 03/13/23) The sending unit is no more than a variable resister. IT does not care about the voltage. However.. if the guage and sending unit dont match correctly, then the gauge will not read correct. It could read stuck to the top or read empty all the time if the resistance range does not match the gauge. So its not dangerous, but may not function correctly. Dangerous.... if you make a spark while connecting any wire and there are gas fumes around, anything could be dangerous, so it best if you connect it with the key off... again,for any wire anywhere around the tractor and gas fumes.

I would hook up the gauge and try it and see how it works. The full is not important, but the empty is very important.

WHY would you chance operating a 6 Volt gauge on 12 Volts?

If the gauge and sender matched/worked on 6 Volts they should work just fine using a voltage reducer.

The exception would be if the gauge is polarity sensitive (as certain ones are) and won't read correctly on 6 Volt (-).

You can even whip up your own power supply for a couple of bucks using a cheap 5 Volt 3-terminal regulator and tricking it into operating a couple of Volts higher.

 

[JMOR]

(quoted from post at 18:06:57 03/13/23)

(quoted from post at 14:48:14 03/13/23) The sending unit is no more than a variable resister. IT does not care about the voltage. However.. if the guage and sending unit dont match correctly, then the gauge will not read correct. It could read stuck to the top or read empty all the time if the resistance range does not match the gauge. So its not dangerous, but may not function correctly. Dangerous.... if you make a spark while connecting any wire and there are gas fumes around, anything could be dangerous, so it best if you connect it with the key off... again,for any wire anywhere around the tractor and gas fumes.

I would hook up the gauge and try it and see how it works. The full is not important, but the empty is very important.

WHY would you chance operating a 6 Volt gauge on 12 Volts?

If the gauge and sender matched/worked on 6 Volts they should work just fine using a voltage reducer.

The exception would be if the gauge is polarity sensitive (as certain ones are) and won't read correctly on 6 Volt (-).

You can even whip up your own power supply for a couple of bucks using a cheap 5 Volt 3-terminal regulator and tricking it into operating a couple of Volts higher.

ot to mention that the fine wire on the sending unit variable resistor may turn red hot and burn up inside the gas tank!
However, if the air fuel mix is too rich (& likely is), it won't explode.

This post was edited by JMOR on 03/13/2023 at 04:09 pm.