Weird wiring issue

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captdiver

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Joined
Apr 16, 2012
Messages
10
I bought a Sweetwater pontoon with a 40 hp OB. The man I bought it from said there was a problem with the fuel gauge and he thought it was a wiring problem. When I turn on the key, the gauge doesn't move. But when I turn on the NAV lights, the gauge moves to 1/2 then when I turn on the key, it jumps closer to full. How the heck do I correct this situation? I don't want to mess up any wiring, but I would like to fix this. Thanks.
 
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Mc Tool

Chief Petty Officer
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Aug 7, 2024
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Sounds like an earthing issue . Check all the negative connections from each load ( vhf , bilge pump , gps , etc ) back to the negative terminal on battery .
Ideally all the negs off each load should go to a common point rather than just be attached to an existing neg wire , and then one main earth back to the battery .
 
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captdiver

Cadet
Joined
Apr 16, 2012
Messages
10
Mc Tool said:
Sounds like an earthing issue . Check all the negative connections from each load ( vhf , bilge pump , gps , etc ) back to the negative terminal on battery .
Ideally all the negs off each load should go to a common point rather than just be attached to an existing neg wire , and then one main earth back to the battery .
Click to expand...
Thanks, I'll check it out.
 
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captdiver

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Apr 16, 2012
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10
Folks, I guess you will have to talk to me like I'm a 10 year old when it comes to marine electronics (I can work all in and over a human body, but this one has me stumped). I cannot find where the ground an anything else is wired together. The ground coming from the gauge travels about 6 inches and there is a bullet connection. I unplug the connection and of course the gauge doesn't work. I took a wire and went directly from the unplugged bullet connection to the negative post on the battery. It did the same when I turned the key on, pegged all the way over. I know for a fact that the tank isn't full because when I look down the side of the tank, I can make out the fuel level. The lights in the gauges don't work either. What do I need to do?
 
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captdiver

Cadet
Joined
Apr 16, 2012
Messages
10
captdiver said:
Folks, I guess you will have to talk to me like I'm a 10 year old when it comes to marine electronics (I can work all in and over a human body, but this one has me stumped). I cannot find where the ground an anything else is wired together. The ground coming from the gauge travels about 6 inches and there is a bullet connection. I unplug the connection and of course the gauge doesn't work. I took a wire and went directly from the unplugged bullet connection to the negative post on the battery. It did the same when I turned the key on, pegged all the way over. I know for a fact that the tank isn't full because when I look down the side of the tank, I can make out the fuel level. The lights in the gauges don't work either. What do I need to do?
Click to expand...
Wait, I'm calling the pink wire the ground!
 
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captdiver

Cadet
Joined
Apr 16, 2012
Messages
10
One I realized I was chasing the wrong wire, I went back and started chasing the black wire. I can't find any issues, so I thought I would start from scratch and rewire it, but the Faria gauge doesn't have the standard terminals on back, it had a plug in module with 4 wires. And the sending unit on the tank doesn't have the normal connections....it is just a small silver box sitting on top of the tank.
 
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