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Fuel tank sensor wiring question

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Old Apr 8, 2026 | 04:49 PM
  #1  
Newfordguy26's Avatar
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Fuel tank sensor wiring question

I'm temporarily running on my rear tank. The selector switch is severely corroded so I was going to wire the rear tank directly to the gauge. I cut the two yellow wires from the selector connection. Leaving me enough room on the pig tail to splice everything back later. I ground the wire going to the gauge and the fuel gauge went to full. When I wired it up to the sensor I don't get anything. I have installed a new sending unit. Could the issue be a faulty ground going from the sending unit?

Thanks.
Chad
 
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Old Apr 8, 2026 | 04:52 PM
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Ground your sending unit wire to the metal of the sending unit, if you can reach it. If the gauge doesn't move like it did on your first test when you grounded the wire, then yes you have a grounding problem to the sending unit.
 
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Old Apr 8, 2026 | 07:21 PM
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Originally Posted by Franklin2
Ground your sending unit wire to the metal of the sending unit, if you can reach it. If the gauge doesn't move like it did on your first test when you grounded the wire, then yes you have a grounding problem to the sending unit.
Would that be "If the gauge does move like it did on your first test" as you are now grounding the sender?
I also thought the senders have a ground as part of the plug as it would have 2 wires or 4 wires?
Just because the sender is new does not mean it is good.
Dave ----
 
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Old Apr 10, 2026 | 10:59 AM
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Originally Posted by FuzzFace2
Would that be "If the gauge does move like it did on your first test" as you are now grounding the sender?
I also thought the senders have a ground as part of the plug as it would have 2 wires or 4 wires?
Just because the sender is new does not mean it is good.
Dave ----
He grounded the wire before and it the gauge moved. If he did indeed have a bad ground to the sending unit, when he touched the wire to the sending unit, the gauge would not move.
 
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Old Apr 10, 2026 | 11:25 AM
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Originally Posted by Franklin2
He grounded the wire before and it the gauge moved. If he did indeed have a bad ground to the sending unit, when he touched the wire to the sending unit, the gauge would not move.
But I thought all sender plugs had 2 wires (sender & ground) or 4 wires (sender & ground and the pump & ground)?
So maybe that ground wire in the plug is bad?
Where did he ground the wire at was it at the cluster of at the tank and what tank? Also if at tank then how could that be without a jumper or a switch to that tank?

I really wonder if the rail harness is a dual tank and the trucks main harness a single tank?
As said I dont know if they will plug together or not? If it was the same plug and they just dont use some of the pins then it could plug together I guess?
But he needs to do more hunting for wires & plug
Dave ----
 
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Old Apr 10, 2026 | 08:12 PM
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For in tank pump I thought it was three wires and shared ground?

Count the pins on the sender or plug
 
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