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Discussion Starter · #1 ·
Hey All,

I traced a very low resistance (yellow) wire north from the tank selector valve to the firewall in hopes of fixing my fuel gauge which is stuck on well beyond full, but it wasn't obvious how to disconnect the plug in at the firewall. Sorry if it's a dumb question, but the last thing I want to do is break it and cause more problems. How does it come undone, or does it ?
 

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Back out the bolt in the center of the connector - the bolt is either 10mm or 11mm.

But you should NOT disassemble anything just to measure resistance through the fuel level wire. The most likely location of the problem is the sender inside the tank. Start by measuring between the sender wires going to the tank (UNplugged from the truck harness). It should be between ~16~160 Ohms. If not, pull the tank plate out. If it is, short the colored (not Black) wire to ground (while everything is connected as normal) and observe the needle with the key in RUN. It should move steadily all the way to Empty.
 

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Discussion Starter · #3 ·
Back out the bolt in the center of the connector - the bolt is either 10mm or 11mm.

But you should NOT disassemble anything just to measure resistance through the fuel level wire. The most likely location of the problem is the sender inside the tank. Start by measuring between the sender wires going to the tank (UNplugged from the truck harness). It should be between ~16~160 Ohms. If not, pull the tank plate out. If it is, short the colored (not Black) wire to ground (while everything is connected as normal) and observe the needle with the key in RUN. It should move steadily all the way to Empty.
Thanks Steve, we'll give that a shot
 

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Hey All,

I traced a very low resistance (yellow) wire north from the tank selector valve to the firewall in hopes of fixing my fuel gauge which is stuck on well beyond full, but it wasn't obvious how to disconnect the plug in at the firewall. Sorry if it's a dumb question, but the last thing I want to do is break it and cause more problems. How does it come undone, or does it ?
Andy, I looked at the wire I think you are talking about. Could it be yellow with a white tracer stripe? Also does the fuel gauge read the same for both tanks? I don't know if tank switch-over is working now or not.
 

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Discussion Starter · #5 ·
Andy, I looked at the wire I think you are talking about. Could it be yellow with a white tracer stripe? Also does the fuel gauge read the same for both tanks? I don't know if tank switch-over is working now or not.
Hey Don, yeah, both tanks are the same and the tank switch over works as you can hear it when you switch as well as that I had to switch tanks when it gave a faulty high reading on the gauge and I was running out of fuel while driving so a switch of tanks solved it and let us keep driving.
 

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Hey Don, yeah, both tanks are the same and the tank switch over works as you can hear it when you switch as well as that I had to switch tanks when it gave a faulty high reading on the gauge and I was running out of fuel while driving so a switch of tanks solved it and let us keep driving.
Glad that often troublesome valve is working. Problem with the yellow/white wire or the gauge itself then. I doubt both sending uniits failed simultaneously although they do fail a lot.
 

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Discussion Starter · #7 ·
Glad that often troublesome valve is working. Problem with the yellow/white wire or the gauge itself then. I doubt both sending uniits failed simultaneously although they do fail a lot.
Ryan scored me a brand new Motorcraft valve a few months ago when the Chinese one off Amazon failed. Yeah, I just don't knpow where on the wire... I'm going to do the wiggle test around the connectors as I suspect something got loose/corroded and then bounced loose or broke.
 
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