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What are the wires running on top of the fuel tank?

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Fishmaster23

Regular Contributor
I'm looking to change out the fuel lines on my fuel tank. Do I need to disconnect the battery when I do this since the fuel tank sending wires are right there? Are these just grounding wires or is there a hot wire also that could cause an explosion if gas from the removed line gets on them?
 
the wires to the sender wont cause you any issues.. BUT, when you have gas fumes in the bilge, there is a high potential for a serious problem from any number of other sources sources that have power in them.... DISCONNECT the batteries (and cover them so nothing can get accidentally dropped, flipped or placed onto them) and the potential for an explosion or fire drops to a minimum
 
The fuel gauge itself has a Positive circuit connected to it for power.

The wire that runs from the gauge to the terminal on the sending unit comes from the sensing side of the gauge.

The fuel tank sending unit itself is basically a variable resistor.

The wire that is connected to the fuel tank's sending unit body is a Negative.
That Negative will be bonded to the ship's Negative system.


Technically speaking, any Positive current that would be seen at the fuel tank's sending unit, would first run through the balancing electro-magnets (coils) within the gauge (these operate the indicator needle).

None-the-less, I too would disconnect the battery while you do this work. Better safe than sorry! :D

Fuel gauge circuit.jpg




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Fishmaster23 said:
I'm looking to change out the fuel lines on my fuel tank. Do I need to disconnect the battery when I do this since the fuel tank sending wires are right there? Are these just grounding wires or is there a hot wire also that could cause an explosion if gas from the removed line gets on them?
Click to expand...

Ayuh,...... It's no argument that disconnectin' the battery is the safest thing to do, before fixin' anything, on anything with a battery,......

But,.......
Of the 3 wires you should be seein', 2 are Grounds,....... Usually a heavier green or black or yellow is used for the bonding system, which electrically combines all of the metal bits in the fuel system, like the fill port, fuel tank, etc.......
It's bonded to the motor's block, which in turn is of course wired to the battery's (-) negative,.....

On the fuel level sendin' unit there'll be 2 wires,......
I think pink is commonly used for the gauge's sender wire, 'n of course, the sender's body will have a black wire to ground,....

As far as any 12v power at the tank, if the keyswitch is Off,........ Nope,.... No power to the tank's sender,.......
 
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