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#1 |
Junior Member
![]() Join Date: Oct 2016
Location: Battle Creek Michigan
Posts: 51
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How to find why fuel gauge doesn't work?
Getting some more stuff knocked out on my daughters 67 C10...
The fuel gauge reads empty, and didn't change when I put fuel in it. The wire going to the sending unit from the dash and under the carpet and seat is hooked up. What is the best way to figure out what isn't working? It could be sending unit, gauge, or wiring, just not sure how to diagnose it all. Any suggestions are appreciated, thanks! Earl |
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#2 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,178
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Re: How to find why fuel gauge doesn't work?
Pull the wire off the sender, turn the ignition on and ground the wire to the body. It should go to full.
- If it doesn't move, try it at the gauge terminal (connect to ground). If it moves at the gauge, then you know the wire has an open (you say empty, but if the gauge was showing full then I would tell you it may have a short to the vehicles body). - If the gauge goes full AND the wire is good, the sender is easy enough to pull and take a look at. Make sure it is grounded to the tank and the tank is grounded to the body. A simple DVOM resistance check between components can show that. - If the gauge doesn't do squat, check the power to it . * If it has power, check that the resistor on the gauge isn't blown. I've seen many a gauge replaced for a $2 resistor that can be replaced! They are sold through truck and car shop. * If it doesn't have power, well, figure out why or jumper power to the gauge directly (at least jumper to figure out if the gas gauge or sender is working).
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC Last edited by demian5; 07-27-2017 at 12:26 PM. |
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#3 | |
Registered User
![]() Join Date: Nov 2011
Location: Dallas TX.
Posts: 1,053
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Re: How to find why fuel gauge doesn't work?
Quote:
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Dale - ApacheIvan 1972 Chevy Custom/20 Custom Camper Highlander http://67-72chevytrucks.com/vboard/s...d.php?t=740479 Original Owner ** Do you have a 1972 Plaid Pickup?** |
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#4 |
Junior Member
![]() Join Date: Oct 2016
Location: Battle Creek Michigan
Posts: 51
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Re: How to find why fuel gauge doesn't work?
Wow, that was fast! Thank you, this forum is awesome... Lots of helpful people here! I would encourage everyone to become a member to help support this, what an asset to the Chevy truck community!
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#5 |
Florida Edition
![]() ![]() Join Date: Oct 2010
Location: Fruitland Park, FL
Posts: 4,043
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Re: How to find why fuel gauge doesn't work?
Could be as simple as the float. I'm on my third aftermarket one now. They are so poorly made that ethanol eats holes in them. One of them actually split but not at the seam!
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70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394 |
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#6 | |
Senior Member
![]() ![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,385
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Re: How to find why fuel gauge doesn't work?
Quote:
The gauge in my driver doesn't work right. Actually, I witnessed it register for a second, when it was cold as heck. It works well enough for me. Reads a pinch over 1/4 when full. At 1/8 it's time to fill up again. ![]()
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly guide (kit) for restoring this truck from the ground up, complete with details including full hardware descriptions. Much of the info. applies to all 67-72 GM. My build thread, with some info. about the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#7 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,178
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Re: How to find why fuel gauge doesn't work?
Sounds like your resistor is bad. My sons 86 operated like that, turned out the resistor on the rear of the gauge was bad.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#8 | |
Florida Edition
![]() ![]() Join Date: Oct 2010
Location: Fruitland Park, FL
Posts: 4,043
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Re: How to find why fuel gauge doesn't work?
Quote:
__________________
70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394 |
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#9 | |
Registered User
Join Date: Mar 2014
Location: Prairieville la.
Posts: 135
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Re: How to find why fuel gauge doesn't work?
Quote:
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#10 |
How did I get this OLD!
![]() Join Date: Dec 2014
Location: Lamont County, AB, CANADA
Posts: 1,050
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Re: How to find why fuel gauge doesn't work?
Mine did the same always on empty. Float had a pin hole in it. Changed that 2 yrs. ago. No issues.
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1967 Oshawa built LWB Fleetside. 327,3 OTT, 515 Vermilion, CST, PS, PB, Shoulder Harness, Tach,Vac, Speed Warning, Choke Delete, Manual Throttle, Fawn interior. Dealer installed A/C 04/2015, N34 Rosewood Wheel 06/2023 Members who I have met personally. Metaldoc, chevnkevin, 62 Longbed, 72LHorn, 72MARIO, YBNORML, TBONE1964, Classic Bowties, Chevemall, Dagnabbitt. |
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#11 | |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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![]() Quote:
Just move the seat forward and carefully remove the sending unit. if the float feels 'heavy'...its full of gas from a pin hole or a crack. Coley
__________________
....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#12 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,178
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Re: How to find why fuel gauge doesn't work?
Fuel and temp gauge for sure, but the oil gauges are mechanical in these trucks from the factory from what I have seen.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#13 |
Registered User
Join Date: Dec 2016
Location: Paris France
Posts: 62
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Re: How to find why fuel gauge doesn't work?
Hi,
I bought an aftermarket sending unit to go with a brand new tank, float was full of fuel two weeks later...reading 0 |
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#14 | |
Registered User
![]() Join Date: Nov 2011
Location: Dallas TX.
Posts: 1,053
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Re: How to find why fuel gauge doesn't work?
Quote:
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__________________
Dale - ApacheIvan 1972 Chevy Custom/20 Custom Camper Highlander http://67-72chevytrucks.com/vboard/s...d.php?t=740479 Original Owner ** Do you have a 1972 Plaid Pickup?** |
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#15 | |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,178
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Re: How to find why fuel gauge doesn't work?
Quote:
You should start here and report back.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC Last edited by demian5; 08-15-2017 at 12:12 PM. |
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#16 |
Registered User
Join Date: Mar 2017
Location: Kansas City
Posts: 47
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Re: How to find why fuel gauge doesn't work?
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#17 | |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,178
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Re: How to find why fuel gauge doesn't work?
Quote:
Pull the wire off the sender, turn the ignition on and ground the wire to the body. It should go to full.
__________________
"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#18 | |
Msgt USAF Ret
![]() ![]() Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,723
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Re: How to find why fuel gauge doesn't work?
Quote:
Remember, when the tan wire is off the sender the gauge reads past full because of the high resistance to ground AKA infinity between the wire and ground. The temperature gauge works just the opposite, when you ground the sender wire the gauge goes to full HOT. Perhaps you had them mixed up. I have done it myself, because they are so similar. VV
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VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
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#19 |
Registered User
Join Date: Dec 2009
Location: bisbee, arizona
Posts: 1,530
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Re: How to find why fuel gauge doesn't work?
pulling my fuel tank out due to serious rust issues, pulled out the sender and discovered that the rheostat switch inside attached to the sender inside the tank was completely rusted away, the lever that attaches to the float, the float itself and the sock filter... all gone. maybe its that junk that keeps clogging my filter every 4 days. Pull your intank sender unit. you may be surprised.
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#20 |
Msgt USAF Ret
![]() ![]() Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,723
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Re: How to find why fuel gauge doesn't work?
read this thread, it will solve fuel gauge issues.
http://67-72chevytrucks.com/vboard/s...d.php?t=640615
__________________
VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
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#21 |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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Re: How to find why fuel gauge doesn't work?
Another thing that can get the gauge out of whack is with a second fuel tank that may have its own sending unit. I have one of those on my truck and there is a toggle switch for it under the dash.
The tank has not been used in, I suppose 10 years...but my buddy flicked that toggle switch to see what it would do out of curiousity. Well the gauge headed for the 3:15 position which confused me at first because he didn't tell me about flicking the toggle switch. However, something in that extra fuel system...perhaps a second sending unit in the other tank?....shut off my primary tanks connection and I lost my fuel gauge until I clicked the switch back. Easy stuff.....just have to keep track of things. all good Coley
__________________
....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#22 |
Registered User
Join Date: Mar 2017
Location: Kansas City
Posts: 47
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Re: How to find why fuel gauge doesn't work?
I'm going to piggy off of this thread as I'm having similar issues. I have not started diagnosing the problem but wanted to see if I could get some expert advice as to where I should start.
Issue: When the gas tank is full, the fuel gauge will read just barely over 1/4. As the tank gets empty, it will drop to 1/8. I've never let it get below that before filling. My first thought would be to check the float. Thoughts? Should I check something else first before pulling the float out? |
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#23 | |
Registered User
Join Date: Apr 2009
Location: Lowell AR
Posts: 360
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Re: How to find why fuel gauge doesn't work?
Quote:
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http://67-72chevytrucks.com/vboard/s...d.php?t=698292 |
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#24 | |
Registered User
Join Date: Mar 2017
Location: Kansas City
Posts: 47
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Re: How to find why fuel gauge doesn't work?
Quote:
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#25 |
BlahBlahBlah
Join Date: Feb 2002
Location: Wa.
Posts: 20,143
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Re: How to find why fuel gauge doesn't work?
What a great thread! Just yesterday I hopped in the truck, turned the key, and my gas gauge zoomed way past the full marker. Ill print this out and get to work on it tonight.
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