Fuel sender and gauge wiring???

[piperca]

I am running two new fuel gauges to my two new fuel tanks. What is the best way to wire these tanks? Is this close:

Pink sensor wire from S on gauge to center post of sender.
Black from I on gauge tapped into the ignition system (not sure of the best place/Volvo diesel gauge panel ... any thoughts?).
Green from G on gauge to screw on sender or grounding tab of tank ... which one??? Also from G to battery ground, correct?
Green from tank fill to grounding tab on tank.

How does this sound? Any input would be greatly appreciated!!!

 

[UncleWillie]

Pink sensor wire from S on gauge to center post of sender.
... OK

Black from I on gauge tapped into the ignition system (not sure of the best place/Volvo diesel gauge panel ... any thoughts?).
... To "I" on any other gage.

Green from G on gauge to screw on sender or grounding tab of tank ... which one??? Also from G to battery ground, correct?
... To "G" on any other gage. You only need to attach it at one place.

Green from tank fill to grounding tab on tank.
... OK. Tank fill, Sender Ground, to Tank Ground. Tank Ground to Battery NEG / Ground BUSS

 

[piperca]

Thanks Bill. If I were to send the gauge ground to the neg/ground buss, behind the main switch panel, and connected the fill ground to the tank and the sensor ground to the gauge, would that not link them all up and be sufficient?

 

[Lincoln253]

It would work but since a fuel gauge is basically just an ohm meter you would want the cleanest circuit possible, plus u want to isolate your 12v system from your hull as much as possible with the exception of shield grounds.

 

[UncleWillie]

Thanks Bill. If I were to send the gauge ground to the neg/ground buss, behind the main switch panel, and connected the fill ground to the tank and the sensor ground to the gauge, would that not link them all up and be sufficient?

That would work.

You just need to get the grounds attached to ground.
The tank is (Hopefully) grounded and the Ground Buss behind the main switch panel is grounded.
Ground the gage to the nearest ground and the sender to its nearest ground.
Both of these grounds already have a much heavier ground wire than you would use if you duplicated the ground path by running another wire between the tank and the gage.

Marine fuel gages are subject to sloshing and effected by a boat that is seldom perfectly level.
The fuel gage reading will always be notoriously inaccurate and should Never be relied upon for anything beyond Almost Full, and Nearly Empty.
Water Temperature, Oil Pressure, Trim position, Tachometer, and Voltage gages all share the main ground buss and do not have separate grounds from each gage to each individual sender.
Don't try to make this harder than it is. Just find the nearest ground and be done with it.

 

[piperca]

Alright, sounds good.

As for the tank being grounded; it is not yet grounded. The tanks are new and will be installed at the time I run the wiring for the gauge. The boat was completely rewired, not that long ago; during which, I installed a fuse panel in the bilge area ... in close proximity to where the fuel tanks are located. The panel has a large neg/ground buss bar. Grounding the tank from its grounding tab to this buss should be sufficient, correct? I've included a photograph of the panel/buss, since it's out fo the boat, pending the tank installation.

 

[Lincoln253]

What material are your tanks made of and what material is your boat made of

 

[piperca]

Tanks are aluminum and boat is fiberglass.

 

[UncleWillie]

Alright, sounds good.
As for the tank being grounded; it is not yet grounded. The tanks are new and will be installed at the time I run the wiring for the gauge. The boat was completely rewired, not that long ago; during which, I installed a fuse panel in the bilge area ... in close proximity to where the fuel tanks are located. The panel has a large neg/ground buss bar. Grounding the tank from its grounding tab to this buss should be sufficient, correct? I've included a photograph of the panel/buss, since it's out of the boat, pending the tank installation.

Correct.

If the tank is metal and grounded, the Sender will likely also be grounded by the mounting screws. (Not all senders)
The ground wire become more relevant when the sender is installed in a plastic tank.

Upon further consideration, running a separate ground back to the gage is of no value.
Technically the Gage does not gave a ground. The lamp in the gage housing uses the ground on the case, but the "Actual Gage" makes no use of the ground.
The Gage uses the "I" Terminal for Power, and the "S" terminal to connect to the sender.
Remove the"G"connection on the Case and the lamp goes Out, But the Gage will continue to indicate fuel level.
The Sender provides the Ground point of the circuit. Routing it back to the lamp ground in the Gage Case is counter productive.

 

[jhebert]

There is a specific recommendation for the installation of fuel tank transmitters (level senders) on conductive surfaces in the American Boat and Yacht Council recommendation ABYC E-9.13.d. It says:

"Grounded Liquid Level Gauge Transmitters (senders) - Grounded liquid level gauge transmitters mounted on fuel tanks or tank plates shall have the transmitter negative return conductor connected directly to the DC Main Negative Bus, the Engine Negative Terminal, or for outboard boats the battery negative terminal or its bus. No other device shall be connected to this conductor. This conductor shall also serve as the static ground and/or the bonding conductor for the tank and fill. If a fuel tank is included in the lightning protection system the conductor between the fuel tank and the DC Main Negative Bus shall be at least 8 AWG. (See ABYC E-4, "Lightning Protection" for additional requirements.)"

The qualification "No other device shall be connected to this conducort," means that this conductor cannot be part of a daisy chain of bonding conductors related to the fuel system. You should run a separate conductor from the sender ground terminal to the battery negative terminal or its bus. In the case of an instrumentation system, it would be better to run that conductor to the same battery negative bus that the electric meter is connected for its negative circuit. This will eliminate any difference in the ground potential for the meter and sender and improve the accuracy of the measurement.

Cf.: https://law.resource.org/pub/us/cfr/....E-09.1990.pdf

 

[piperca]

Excellent information; thank you both! I think I am now clear on what needs to be done ... fingers crossed ... HA!