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#1 |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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fuel gauge
fuel gauge on 72 k20 not working. ok when parked in fall. where to start. all other gauges appear ok
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#2 |
Senior Member
![]() Join Date: Nov 2013
Location: East Tennessee
Posts: 2,225
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Re: fuel gauge
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1967 C10 Step side 1968 C10 Step side 1970 Chevrolet K/5 Blazer 1972 Chevrolet K/5 Blazer ............. ![]() |
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#3 |
Registered User
Join Date: Jul 2008
Location: Eastern Oregon
Posts: 2,414
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Re: fuel gauge
I had an inoperative fuel gauge. I replaced the sending unit, rechecked all the continuity. Eventually I determined that the needle was just stuck in place. Had the cluster out and just moved it a bit with my finger. Original gauge still works fine. Can’t say that about a lot of the new Chinese knockoffs.
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71 C-20 07 Magnum RT AWD |
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#4 |
Registered User
Join Date: Jan 2015
Location: central oregon
Posts: 279
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Re: fuel gauge
Take the sending unit wire of sender, ground it out. If gauge moves its the sender. This was my problem ha
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#5 |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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Re: fuel gauge
thanks for replies. got some work to do. i have a relocated tank under bed and it may be a process to get to wire
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#6 |
Senior Member
![]() ![]() Join Date: Jan 2005
Location: CA
Posts: 6,219
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Re: fuel gauge
Initially you could just access the tan sender wire where it plugs into the fuse panel under the dash. Unplug it there and ground the fuse panel Fuel Gauge terminal to see if the gauge moves to Empty.
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#7 |
Senior Member
![]() Join Date: Oct 2015
Location: Williamston, Mi
Posts: 902
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Re: fuel gauge
I put a new suburban tank under the back of my truck 3 years ago, last summer after final assembly I got the truck out and was on empty all the time. Pulled the sending unit out and the float was full of gas. Bought a new plastic float for a jeep as recommended by folks here, solved my problem.
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#8 | |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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Re: fuel gauge
Quote:
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#9 |
All stock and staying that way
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Location: Elkland, PA
Posts: 2,064
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Make sure the tank is grounded to the chassis.
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1970 K/5 Blazer CST 4WD, TOTM winner December 2024! Medium Bronze poly, 93k ACT. miles, 350, 4 speed, rear positraction, 16.5" x 8.25" HD Kelsey Hayes wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration finally getting close to completion.. ![]() 1970 K20, To be a clone of my Grandfather's K20, Dark Blue poly, 350, 4 speed, 16.5" X 8.25" Kelsey Hayes wheel option, tilt, tach, vacuum, AM radio. Latest project truck 1972 Cheyenne Super 20 2WD, Dark Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... ![]() 2017 Sierra 1500 SLT 4WD, Black, 46k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 67k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
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#10 |
Senior Member
![]() ![]() Join Date: Jan 2005
Location: CA
Posts: 6,219
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Re: fuel gauge
It should be a tan wire that plugs in at the end of the fuse panel.
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#11 |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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Re: fuel gauge
thanks for the picture locate, I will check it out
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#12 |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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Re: fuel gauge
the gauge is registering E now. when grounding out would gauge peg hard to left (empty side)
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#13 |
Senior Member
![]() ![]() Join Date: Jan 2005
Location: CA
Posts: 6,219
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Re: fuel gauge
Disconnecting the tan wire from the fuse panel with the ignition on should cause the needle to move way past Full to around the 3 o'clock position. Then grounding the fuse panel terminal should move the needle back to Empty. If it acts that way, then your gauge is likely good.
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#14 |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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Re: fuel gauge
gauge cks good. thanks for the pic.
guess i need to make sure wire from fuse panel to tank is good. tank and sender not very old. I'm hearing alot of parts we are getting are from China and not good quality |
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#15 |
Registered User
Join Date: Jan 2015
Location: central oregon
Posts: 279
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Re: fuel gauge
Run a cheap piece of wire to sender to try or just take the 2 minutes and remove the sender to test
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#16 |
Registered User
Join Date: Nov 2018
Location: Tieton,WA
Posts: 62
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Re: fuel gauge
looks like wire from fuse pnl to sender is good. it would be a quick job to remove sender if it wasn't located on top of fuel tank and pu bed sitting over the relocated fuel tank was removed
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#17 | |
Senior Member
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Location: Northern Nevada
Posts: 7,384
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Re: fuel gauge
Quote:
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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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#18 |
Senior Member
![]() ![]() Join Date: Jan 2005
Location: CA
Posts: 6,219
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Re: fuel gauge
Since the gauge returns to Empty when you have the sender wire connected, that tells me the sender wire is providing a path to ground. Your tank is likely adequately grounded. My guess, as others have already mentioned, is that your sender float has filled with gas and has sunk to the bottom of the tank.
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#19 |
Senior Member
![]() Join Date: Feb 2022
Location: Ca
Posts: 702
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Re: fuel gauge
Grounding the wire at or just in front of sender would have eliminated a few steps. I agree. You have a bad sender. Either a result of a faulty float or potentiometer in the sender. Either requires pulling the sender to verify. You can put a ohm meter on the sender. Swinging the float arm should move your meter from 0 to 90 ohms.
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#20 |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,874
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Re: fuel gauge
Six years ago when I bought my '71, the fuel gauge did not work.. The brass float had rotted out and sunk to the bottom. I installed an LMC sending unit and the gauge worked perfectly. 3 - 4 months later, the gauge quit working again. The solder joint on the float had failed, the float filled with gas and subsequently sunk. LMC provided me with a replacement sending unit. A few weeks later it failed. I returned the sending unit and LMC issued a refund. I bought a sending unit from Classic Industries, and examined the sending unit to see if I could determine the reason for the solder failure.. The float fitted tight in the "loop" of the arm. I removed the float and opened the loop enough that the float was loose but well captured.. This all happened in 2018.. Today that same float/sending unit is in my truck, working perfectly..
As you know, solder doesn't have much structural strength. I believe the loop fits the float too tightly, causing stress on the solder joint, and it will eventually fail. Loosen the loop , releasing that tension and the premature float failure issue is resolved. |
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