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Hi guys. the boat was inspected and was found this: "no continuity was found between the aluminum fuel tank and the vessel's DC  negative/engine. Investigate further and correct as necessary ensuring the fuel tank is grounded to the vessel DC negative engine resistance between the two is less than one ohm. ABYC H24" Soooooo....

1) what am I looking in here?

2) a broken wire?

3) DO I have to make one?

4) what am I looking for?

5)  or where should I look for?

6)  is this wire should be connected to the tank itself or the sender or somewhere else?

7) my fuel gauge seems not too accurate. in the water shows something different than on the trailer. ex: in the water shows 1/2 on the trailer full! so, could this be the problem? or a sender problem? or a gauge problem? all the above? 

 

thank you guys! 

this is a 2004 Chap 260 Signature

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I would ground the tank any way I can. 

 

Boat fuel gauges are not very accurate. When under way, I use my GPH (gal per hour) to get a better feel for what is left in the tank.

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Marine metal fuel tanks are not grounded, they are part of the bonded network, having nothing to do with the 12 VDC negative system. Every metal part on the boat is connected by a stranded wire, typically green, daisy chained together and terminated on copper buss bars located on the transom interior. The fact that your tank does not show continuity with the engine block is disconcerting for sure, but my guess is that perhaps the tank may still be connected to the buss bar and that the engine block is not, even though the engine is still connected to it's negative battery terminal. I would find the bonding buss bar and check between it and the tank and then it and the block. Your fuel gauge should have it's own dedicated ground wire which is connect to the negative side of the 12 vdc power network. Similar to a home AC power distribution system, neutral and ground are not the same thing or even the same wires even though both have the same electrical potential, unless something fails. W

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On 10/1/2020 at 7:42 PM, Wingnut said:

Marine metal fuel tanks are not grounded, they are part of the bonded network, having nothing to do with the 12 VDC negative system. Every metal part on the boat is connected by a stranded wire, typically green, daisy chained together and terminated on copper buss bars located on the transom interior. The fact that your tank does not show continuity with the engine block is disconcerting for sure, but my guess is that perhaps the tank may still be connected to the buss bar and that the engine block is not, even though the engine is still connected to it's negative battery terminal. I would find the bonding buss bar and check between it and the tank and then it and the block. Your fuel gauge should have it's own dedicated ground wire which is connect to the negative side of the 12 vdc power network. Similar to a home AC power distribution system, neutral and ground are not the same thing or even the same wires even though both have the same electrical potential, unless something fails. W

Do the aluminum tanks have a bung or other provision for attaching this bonding wire?  Where would I look for this?  I have a boat with an aluminum tank that is not original and I do not believe it is bonded. 

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17 hours ago, Dustin Mustangs said:

Do the aluminum tanks have a bung or other provision for attaching this bonding wire?  Where would I look for this?  I have a boat with an aluminum tank that is not original and I do not believe it is bonded. 

I've see dedicated lugs welded to corner beads, and have also seen them landed to the fuel gauge sender flange screws. Look for a 10# stranded green wire, and if it's not there, add one and land the other end to your aft bonding buss bar. W

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  • 2 weeks later...
On 10/1/2020 at 7:42 PM, Wingnut said:

Marine metal fuel tanks are not grounded, they are part of the bonded network, having nothing to do with the 12 VDC negative system. Every metal part on the boat is connected by a stranded wire, typically green, daisy chained together and terminated on copper buss bars located on the transom interior. The fact that your tank does not show continuity with the engine block is disconcerting for sure, but my guess is that perhaps the tank may still be connected to the buss bar and that the engine block is not, even though the engine is still connected to it's negative battery terminal. I would find the bonding buss bar and check between it and the tank and then it and the block. Your fuel gauge should have it's own dedicated ground wire which is connect to the negative side of the 12 vdc power network. Similar to a home AC power distribution system, neutral and ground are not the same thing or even the same wires even though both have the same electrical potential, unless something fails. W

well... this fuel thank as you should know, it is buried under the holding and fresh water tanks and not very accessible! I did checked the continuity between the tank and the engine block.. nothing happened! I did checked also to the BUS BAR with no luck! so what I did, was to grab a wire and connected from the tank structure itself and wired to the negative side with aonther wire. I guess that would take care of it.

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Bonding & grounding are SUPPOSED to be for 2 different reasons or conditions. Even the US CG  can not keep it straight nor do marina people.

I boats.  The purpose of BONDING to to help prevent the EATING UP of metal boat parts in the water around the boat. Sounds simple until metal parts are BONDED TOGETHER. THen we reach a metal drive shaft connected to a transmission. Which is connected to the ....-  NEGATIVE post of the batteries.

So what really happens is all the  parts in water are at minus 12 volts . IF  IF  the drive is ISOLATED from the engine somehow.  Insulating drive coupling ?? 

Back to the problem gas tank. If it is somehow connected to the - minus 12 vdc battery terminal?  What COULD happen if a + POSITIVE wire touches the tank ?  SPARKS ?  until a C B trips off ? 

How many  metal gas tank sensors are COMPLETLY ISOLATED from the metal of the tank ?  As people repair things it gets difficult to follow a bad electrical code.  Boat industry IS A SELF REGULATED GROUP.  THey can do what they want to do in a lot of things.     :thththsoapbox2-1:

My age will show on this topic. BUUTT at 1 time ALL boats were wired to the National Electrical Code. The same one a licensed electrician follows. Reason was... Some boats had land line voltages to shock & kill.    :thththsoapbox2-1:

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  • 2 weeks later...
On 10/1/2020 at 4:42 PM, Wingnut said:

Marine metal fuel tanks are not grounded, they are part of the bonded network, having nothing to do with the 12 VDC negative system. Every metal part on the boat is connected by a stranded wire, typically green, daisy chained together and terminated on copper buss bars located on the transom interior. The fact that your tank does not show continuity with the engine block is disconcerting for sure, but my guess is that perhaps the tank may still be connected to the buss bar and that the engine block is not, even though the engine is still connected to it's negative battery terminal. I would find the bonding buss bar and check between it and the tank and then it and the block. Your fuel gauge should have it's own dedicated ground wire which is connect to the negative side of the 12 vdc power network. Similar to a home AC power distribution system, neutral and ground are not the same thing or even the same wires even though both have the same electrical potential, unless something fails. W

+1, you are looking for a GREEN wire from the tank to the main DC negative bus bar in the engine bay.

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On 9/30/2020 at 12:42 AM, ALEX JARA said:

Investigate further and correct as necessary ensuring the fuel tank is grounded to the vessel DC negative engine resistance between the two is less than one ohm.

Look for the bonding buss where green bonding wires converge and NOT for the DC negative aka ground buss where yellow (or old days, black) wires converge. See both busses in a picture below showing example of Chaparral electrical rigging.

The resistance between the GREEN bonding buss and the tank should be next to nothing. If no continuity, bond the tank yourself or get some professional help. If the tank's boding wire connection point is buried you might be able to rig one using tank's existing metal fittings - get a professional opinion on that first.

208480767_BONDINGVSDCNEGATIVEAKAGROUND.png.f11ee50a44fe8cdc20d0d9f0109fb9a0.png

 

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On 10/31/2020 at 1:59 AM, Rambo said:

Look for the bonding buss where green bonding wires converge and NOT for the DC negative aka ground buss where yellow (or old days, black) wires converge. See both busses in a picture below showing example of Chaparral electrical rigging.

The resistance between the GREEN bonding buss and the tank should be next to nothing. If no continuity, bond the tank yourself or get some professional help. If the tank's boding wire connection point is buried you might be able to rig one using tank's existing metal fittings - get a professional opinion on that first.

208480767_BONDINGVSDCNEGATIVEAKAGROUND.png.f11ee50a44fe8cdc20d0d9f0109fb9a0.png

 

oh ok! ill look for it!! thanks for the great info!

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