Fuel system issue.
Logistics Pro
Joined: Nov 2013
Posts: 3,922
Likes: 1,192
From: Mojave, Ca
Yep. remove the screw from the terminals, clean them with a wire brush, and re-install it. I have no idea what that electrical component is. I dont think it belong on your truck. Does it have wires coming out the back?
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Mountain Pass
Joined: Jan 2023
Posts: 144
Likes: 11
Nope. It just seems like a semi transparent 3 prong plug of some kind. There have been so many weird things that I have found on this truck. It is my first vehicle so forgive my lack of knowledge. So are both my sending units bad?
Logistics Pro
Joined: Nov 2013
Posts: 3,922
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From: Mojave, Ca
Dont know yet. Your gauge is working backwards, for some reason. With the switch disconnected, you should be seeing a full gas tank. Usually, when the sending unit wears out, it goes "open" and your gas gauge maxes out. Does your gas gauge usually sit at empty?
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Mountain Pass
Joined: Jan 2023
Posts: 144
Likes: 11
Yep. It has said empty ever since I bought it. I will clean up the ground tomorrow. When it is light out.
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Logistics Pro
Joined: Nov 2013
Posts: 3,922
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From: Mojave, Ca
It's rare, but some times your sending unit floats develop a hole, and sink to the bottom of the tank, so your gauge shows empty. But I would take another look at your fuel gauge with a grounding wire and your sending unit resistance before dropping the tanks.
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Mountain Pass
Joined: Jan 2023
Posts: 144
Likes: 11
Well results are in. I took off the ground, cleaned it up, and put it back on, and... same thing as before. I also just tried out my new code reader and I get code 542. Also know as fuel pump secondary circuit fault. What should I do next?
Trailering
Joined: Feb 2023
Posts: 18
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As far as the truck shutting off goes can you bleed the fuel rail? Then use the front tank and turn the key on. Note the fuel rail pressure increase and turn the key off then bleed it off. Then switch it to the rear tank and turn the key on then check the fuel rail for pressure. This takes a minute and should at least confirm that your rear tank is or isn't providing any pressure assuming the switch is working. If there's no pressure on the rear tank then that shows the switch is working. Your check valve on one of the pumps could be bad. The rear pump could be stuck closed or the front pump could be stuck open stealing your fuel pressure(Edited. There is no fuel selector valve. I stand corrected).
Last edited by 347Windsor; Feb 3, 2023 at 09:44 PM.
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Mountain Pass
Joined: Jan 2023
Posts: 144
Likes: 11
when the switch is disconnected it does do that. I hope that means that I have been doing things things wrong and everything is working right, because the tests where I was grounding certain wires was all done with the switch off.
Logistics Pro
Joined: Nov 2013
Posts: 3,922
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From: Mojave, Ca
Your gauge seems to be working correctly, which is good. But I wanna make sure the gauge is ok before I send you in a wild goose chase.
with the switch removed, connect the yellow/white wire to ground. Turn on the ignition switch. The gauge should drop to zero. Does it?
with the switch removed, connect the yellow/white wire to ground. Turn on the ignition switch. The gauge should drop to zero. Does it?
Hotshot
Joined: Jun 2015
Posts: 12,784
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Test resistance with the key off. In order to short a circuit to ground, you need voltage in the circuit ie the key on.