Fuel filler grounding..

MikeyThumbs

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Hi everyone.. I’m in the process of replacing the fuel tank and fill/vent lines on my 1983 tournament. There is a grounding wire on the current fuel fill which broke. Can I just run a new wire from an open terminal on the bus of my Blue Sea Systems fuse block that I am in the process of installing? If not, how else would I “ground” the fill?
 

seasick

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Assuming the tank is grounded ( metal tank ) then the ground for the fill should go to the same ground source. That probably would be closer to the batteries than the helm but I am not sure, The old fuel fill may be spliced at the tank ground point. See if you can follow it.

If you can get to where that ground is broken, it would be OK to splice using a crimp connector with adhesive lines shrink tubing over it. The fill ground is not to provide a ground signal for any devices, it is there to allow built-up static electricity to be dissipated.
 

MikeyThumbs

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So I should run a wire from the new fill cap to the tank, correct? As long as the fuel sender circuit is complete I should have a ground?
I’m new to boating in general so I’m trying to figure out and understand how everything works as I clean it up and get everything in order..
From what I gathered, the motor is grounded via a zinc plate under the transom bracket.. so as long as it’s connected to the starting batteries negative side (weather it be directly or through a bus) should be good?
Could I not just run a new wire from the zinc plate to the tank and then fill cap, if the plate provides the grounding for the motor?
 

MikeyThumbs

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I just pulled off more panels and crawled under the console. It seems that the ground for the fill cap was pulled from the black wire that feeds lighting to the port side (blue and black wire). The green ground from the fill cap connects via butt splice into the black wire and these blue and black wires are just dead ended, coiled up under the panel, assuming this was an option that was not chosen for this model.
 
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SkunkBoat

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Models and years vary but..
Usually, there is a green or green/yellow wire from a tab on the the tank to the Neg battery terminal. Its possible that it is black.
Sometimes there are three green wires bundled to one connection on the Neg Battery. These are fuel grounds.

Technically, the fuel system grounds should be Green (or Green/yellow) and go directly back to the batteries. They are not supposed to be part of or shared by the Negative 12V circuit.
So you should not connect it to the neg bus of the fuse block.
 

MikeyThumbs

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Models and years vary but..
Usually, there is a green or green/yellow wire from a tab on the the tank to the Neg battery terminal. Its possible that it is black.
Sometimes there are three green wires bundled to one connection on the Neg Battery. These are fuel grounds.

Technically, the fuel system grounds should be Green (or Green/yellow) and go directly back to the batteries. They are not supposed to be part of or shared by the Negative 12V circuit.
So you should not connect it to the neg bus of the fuse block.
Ok, got it. Sorry, when I said bus I meant a separate “grounding” bus that is ran from the negative terminal of the battery strictly for the fuel tank and filler.
 
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seasick

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The zinc plate under the transom if attached to the motor bracket is your sacrificial anode. It is not the same as a grounding bar which can also be a sacrificial anode but the wiring is more important..
Take a look at your thru hull fittings inside the bilge, particularly the seacocks. Check to see of there is a grounding wire connected to the seascock or thru nut. If so you have a grounding bus and the gas filler should connect to that. Grounding busses typically require direct ground runs from protected devices. If you don't have a grounding bus then connect the filler grounf to the tank ground assuming that is a good ground. If it isn't most likely you fuel gauge will not work correctly.