Fuel Guage Wont Read on Drivers Side Tank

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fallguy

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Minot, ND
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1986
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Silverado K10
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350
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Last year I installed a new fuel tank selector valve as the old one ceased to function. with the new valve came a new pigtail. also i replaced the switch in the cab. anyway, about a month ago, my drivers side tank ceased to read it simply went to way beyone full (about the 3 o'clock position). i thought sending unit so i replaced that on that particular tank. no change. i checked my splicing on the new pigtail and all was solid. however, in messing around down there it would start to work, and then when i shoved all the wires up and way, then it stopped. i couldnt get it to start working again no matter what wires i messed with.

today i followed the wire from the fuel sending unit to the plug on the selector valve and up to the engine. no breaks in the wires. the passenger side tank has never stopped working or reading correctly. the selector valve functions as it should.

someone help!!! why wont my guage read on that drivers side tank!?! it works right on the other tank and as i said all wires are good and connections are solid.

i ran my test light on the pigtail when it was unplugged. the third wire would light up wether i was on switched to the driver or passenger tank. however, when i put the tester in that port it would make the passenger tank guage move, but when i would switch to the driver tank the guage would not move. i have no idea what the hell that means, but i am just sharing what i found.

HELP!!!!
 

crazy4offroad

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Sounds like a bad ground on the driver's side tank. Check the ground from the frame to the tab on the sending unit top where the hoses hook up.
 

fallguy

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Sounds like a bad ground on the driver's side tank. Check the ground from the frame to the tab on the sending unit top where the hoses hook up.

did that when replacing sending unit. ground is solid and making clean contact. if its grounded wrong it goes to way past empty (or so im told) and if its other wiring it goes way past full...which is my issue.
 

fallguy

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Silverado K10
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350
Solved

was given the attached wiring diagram from the 72-87 site and pinpointed the issue to the pigtail i wired in for the new tank selector valve. the light pink wire reporting to the guage was not connecting. cut out all butt connectors, reconnected all wires and soldered them. problem solved.

attachment.php
 

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HotRodPC

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Awesome. Thanks for the update and fix. We've got that schematic on here somewhere but it never hurts to have it twice.
 

Illuminati

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This is good to know...I'm having the same problem with the drivers' side tank but haven't had the time to pull it down and looky. I have a feeling that its a broken wire or a bad ground or something of the sort...at least I hope.
 

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