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Thread Tools | Display Modes |
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#1 |
Registered User
Join Date: Aug 2005
Location: Ottawa County, Michigan
Posts: 63
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Fuel gauge problem/question
The fuel gauge in my 72 K5 Blazer was never working right... So I pulled the tank, replaced the sending unit with a new one, installed a new fuel gauge wire lead to the fuse box, made sure the ground was clean and lubed and the fuel gauge still only moves a bit off 1/4 tank.
I checked for power at the fuse box power lug with just a tester light so far and it barely lit up the tester light. I pulled power from another 12v source on the fuse panel for the sending unit and the gauge went to full but back to 1/4 tank when I cut power. I did replace the resistor on the back of the instrument panel with one (used one) off another cluster I had... and it worked for a while but now it's back to 1/4 tank even though we put in enough gas that should bring it well over 1/2 tank. ANY IDEAS TO HELP CORRECT THIS PROBLEM WOULD BE APPRECIATED !! THANKS. |
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#2 |
All about them K’s
![]() Join Date: Jun 2014
Location: Land of Entrapment
Posts: 6,374
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Re: Fuel gauge problem/question
I bet it’s the resistor again. That’s what mine did when the same when the resistor was bad.
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Tyler '57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888 '72 K20 Cheyenne http://67-72chevytrucks.com/vboard/s...d.php?t=662879 ‘69 K10 SWB http://67-72chevytrucks.com/vboard/s...d.php?t=805206 '98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 315/75/16's ‘87 IROC-Z all original 50K mile survivor TPI 305 IROC Blue ‘10 Camaro 2SS/RS Aqua Blue Metallic #93 -version 2.0 ![]() |
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#3 |
Cluster King
![]() Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,263
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Re: Fuel gauge problem/question
Typically it is the resistor that will cause this,
Truck and Car shop in Orange CA sells new porcelain style resistors. If you have a temp gauge, you can use the resistor from it to test. I have never had another problem cause the "1/4 tank" issue.
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Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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#4 |
Registered User
Join Date: Aug 2005
Location: Ottawa County, Michigan
Posts: 63
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Re: Fuel gauge problem/question
Thanks all.... I'll look into that resistor.
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#5 |
Registered User
Join Date: Aug 2005
Location: Ottawa County, Michigan
Posts: 63
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Re: Fuel gauge problem/question
I checked with Truck and Car shop in Orange CA. They do not have any in stock; their supplier does not sell them anymore. These resistors are almost as scarce as toilet paper was...
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#6 | |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,695
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Re: Fuel gauge problem/question
Quote:
I have repaired numerous gauges using a commonly available 85 - 90 ohm 3 watt metal film resistor.. The leads are long enough to fashion loops that fit over the posts of the gauge.. The resistors are available from Mouser electronic supply... Their warehouse is located in the Dallas, Texas area... |
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#7 |
Registered User
![]() Join Date: Dec 2013
Location: Dunwoody,Ga
Posts: 443
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Re: Fuel gauge problem/question
A question for RustyPile.
Why are the stock resistors apparently wire wound over a flat board? Thanks |
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#8 |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,695
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Re: Fuel gauge problem/question
It's designed to specifically fit the gauge. Referred to as a wire wound resistor. The wire is special resistor wire, similar to the resistor wire used in a points type ignition... The resistance is determined by length of the wire..
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#9 |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,695
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Re: Fuel gauge problem/question
Mouser's website can be difficult to navigate for some people.. Here's a link to the resistor I use:
https://www.mouser.com/datasheet/2/4...fs-1762753.pdf |
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#10 |
Registered User
Join Date: Aug 2005
Location: Ottawa County, Michigan
Posts: 63
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Re: Fuel gauge problem/question
Thanks RustyPile. I'll run a test on my resistor. I do have a lead on a new resistorI'm following up on.. but if that falls through and I truly need a new resistor, I'll take your advice on the replacement one.
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#11 |
Registered User
Join Date: Aug 2005
Location: Ottawa County, Michigan
Posts: 63
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Re: Fuel gauge problem/question
The resistor tested fine... but I cleaned it up a bit and reinstalled it... now it seems to be working... go figure! Who knows... as long as it's working, I'm good with that. Thanks all !!!
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#12 |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,695
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A large portion of the electrical problems with these old trucks can be traced to corrosion and bad connections.. The worst thing a person can do is to indiscriminately throw parts at it hoping something will stick.. Job well done Mr. Copper... You used a systematic approach and found the problem...
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#13 |
Registered User
Join Date: Aug 2005
Location: Ottawa County, Michigan
Posts: 63
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Re: Fuel gauge problem/question
I appreciate the pat on the back there RustyPile !! But wouldn't you know it... we go to fill it up and it stays there. A little ways down the road, it goes to full.. then after it sits a bit... and we start it up again... the fuel gauge doesn't register right.. It's got to be a bad connection or, the float I would think may be sticking.. but we replaced the sending unit with a brand new one! We tested it's function before we put it in the tank and it tested fine... We tested a new wire lead to that we bought and it worked just as well as the original. I really don't want to pull the tank again... this is aggravating.. so we'll just keep topping off the tank till time to put it in winter storage. We'll tackle it again next spring once the snow is gone and it warms up. We don't put the top on it... it stays in storage.. it's a double walled top. I have a single wall top but will probably get rid of it. I don't have the time to clean and restore it anyway. Thanks again.
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#14 | |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,695
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Re: Fuel gauge problem/question
Quote:
If this doesn't correct the balky gauge, check and clean each and every connection associated with the fuel gauge circuit -- EVERY ONE.. Good luck with your troubleshooting.. Post your findings... |
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#15 | |
Registered User
Join Date: Jan 2018
Location: Lemoore, CA
Posts: 74
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Re: Fuel gauge problem/question
Quote:
I’m definitely looking for a link here as I’m never gonna be able to navigate to the right resistor without having my hand held. Lol. |
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#16 | |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,695
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Re: Fuel gauge problem/question
Quote:
Here's the technical description. Metal film, axial lead, 3 watt power rating.. They are obtainable from Mouser electronics, digikey, and any locally owned electronic supply facility. Due to your unfamiliarity, I'd suggest, instead of placing an online order, you give the source a phone call and place the order personally. Here's links to a couple suppliers I use. https://www.mouser.com/?utm_source=b...Brand%20Mouser https://www.yellowpages.com/beaumont...ronics-5943025 Last edited by RustyPile; 03-03-2022 at 10:37 PM. |
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Tags |
12v, gas, gauge, instrument cluster, sending units |
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