Grounding Fuel Fill and Fuel Tank

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Grounding Fuel Fill and Fuel Tank

Postby Onplane » Thu May 04, 2017 6:14 am

I'm sure there is already a post for this subject, but I couldn't seem to find exactly what I was looking for... So I apologize in advance if this is repetition...

I have a plastic Moeller Fuel tank, and I bought the Moeller fuel tank installation kit.

The instructions, as you can see in the picture, looks like it shows a grounding wire coming from the underside of the fill neck, to ground. The place where it attaches on the neck looks almost like it's a set screw or something you'd just slip an electrical connector onto. However, the neck itself is completely smooth (no set screw, no threaded hole, nothing). In other words, no obvious electrical attaching point.

Additionally, there are some bold warnings not to trap the ground wire between the neck fill and the fill hose.

So my question is... where do I attach the ground wire on the fill neck, and how?

The fill neck is currently attached with 3 wood screws into the top deck, but I suppose I could replace one of these with a bolt and ground to that, but I'm not sure that's what is required.

The fuel vent line apparently needs to be grounded too. However, I don't see any attachment point for that either. If I use a spot on the metal tie strap does that even provide any benefit?

Finally, with my very limited experience with electrical... my plan is to route all grounding wires to a bus bar that that then goes to the negative terminal of the battery. Is that understanding correct? The product literature on grounding is quite confusing seeing as how I don't have a "mast, lightning ground bar, or engine block" to ground to...


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Re: Grounding Fuel Fill and Fuel Tank

Postby Soloboat » Thu May 04, 2017 8:07 am

Using a through bolt to the underside to attach a ground wire is the way to go I did just that however just make sure that there is continuity from fill to your ground verify by using an ohm meter. Connecting to a neg. bus is ok too
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Re: Grounding Fuel Fill and Fuel Tank

Postby Onplane » Thu May 04, 2017 1:30 pm

Found a pic of what I was trying to explain...


Sounds like a plan. Now, the vent line has a metal thru hull connector that's supposed to be grounded as well, any suggestions on how to do this?

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Re: Grounding Fuel Fill and Fuel Tank

Postby BillW » Thu May 04, 2017 10:10 pm


On that drawing shown above, the ground wire should connect the filler neck to the fuel sender plate ground connection,
and then to ground.

You say you don't have an engine block, but whether your motor is inboard or outboard, it has a block. If it has electric starting, the
negative battery cable goes to the block, and that is grounded to the water thru the drive shaft, lower unit, etc.

I think that Glen-l offers electrical system drawings now; probably has a lot of good info.

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Re: Grounding Fuel Fill and Fuel Tank

Postby Bill Edmundson » Fri May 05, 2017 7:53 am

All metal parts of the fill and tank system should be grounded to each other and then to the boat ground. This so all parts are at the same static potential and can't spark. The vent has a serrated washer under the nut. Put the ground under it, then tighten back down. Go to the filler bolt then to the tank, then to the boat ground.

I'm surprised that they don't show double clamps on the vent line.

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