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#1 |
Registered User
Join Date: Jan 2013
Location: Jasper, IN
Posts: 948
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Gas Guage Prob's
I have a 78/79 k10, A 1/2 ton lwb. I had to buy a new gas tank and also got a new sending unit, got it in n wired up good... But my gas guage won't go below a half a tank. This is my 2nd guage as my first one wouldn't sit still, it just bounced from E to F every time i hit a bump. Is my 2nd guage bad as well? I'm going to run after market guages in my bezel but until then i need a good one. Do any aftermarket's (prefferbly equies so it matches) make a guage that will work woth our sending units? Thanks
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#2 |
Registered User
Join Date: Mar 2012
Location: San Antonio, Tx
Posts: 784
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Re: Gas Guage Prob's
all the wires making good contact?
clean maybe the terminals where the gauge prongs go into maybe check behing your cluster for a lose ground or loose sender wire my gauge bounces too when i hit a bump, when my tank is full it dosent bounce but once it has a few gallons out, the gas sloshes and gives a false reading you can check your gauge with 2 C batterys
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San Antonio, TEXAS -Frog -I'm a valet and well I've driven BMWs, Mercedes, Porsche,Bentlys, fiats, Hondas, etc and well even do I like a few features, I love my shortbed, it dosent bore me out, just press on the gas and you'll remember why you love it. |
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#3 |
78 Big10 454
![]() Join Date: Jul 2008
Location: Pismo Beach, CA
Posts: 838
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Re: Gas Guage Prob's
I had the same problem with my square. I tracked down the wiring and found a spot where the insulation had worn off and would ground to the frame whenever I hit a bump or rough road. My problem was where the wire ran along the inside of the frame, right below the passenger side door. Electrical tape can be a life saver.
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1978 Chevy SWB C-10 2WD 454/400 |
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#4 |
Moderator
![]() Join Date: Oct 2008
Location: Wentworth, NH
Posts: 4,951
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Re: Gas Guage Prob's
Bouncing is normal in an air core meter. It can be mitigated somewhat with an injection of some special silicone damping gel. Gauge repair guys can do this for you pretty quick.
Not dropping below 1/2 tank indicates increased resistance somewhere in the circuit. Is the ground wire from the sender to the frame making good contact? You can bench test a fuel gauge with a charged 12v battery, 4 alligator clip test leads, and a couple 1/2W resistors (100ohm and 50ohm 90 & 45 would be better but 100 & 50 are close enough). It's worth noting that the resistors can get VERY HOT so be careful of where you place them... not on the kitchen table or those greasy rags. ![]() If your gauge passes these tests it's not the problem.
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1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...
And please let us know if and how your repairs were successful. |
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#5 |
78K & 79C Jimmys
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
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Re: Gas Guage Prob's
my 78 Jimmy bounced
when I changed from idiots to tach and cluster i had to add a seperate ground for the fuel gauge ground it stopped my 79 I was worried changing to a spectra unit this summer it would bounce nope if it's working right, grounding the sender wire is E,off is over F I'd check the tank ground for sure
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John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350 |
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#6 |
Another Day, Another Dollar
Join Date: Nov 2008
Location: North Vancouver, BC
Posts: 1,316
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Re: Gas Guage Prob's
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-78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square" ![]() |
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#7 |
Another Day, Another Dollar
Join Date: Nov 2008
Location: North Vancouver, BC
Posts: 1,316
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Re: Gas Guage Prob's
My fuel gauge bounces on both tanks, always has, I thought it was supposed to do that.
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-78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square" ![]() |
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#8 |
Registered User
Join Date: Jan 2013
Location: Jasper, IN
Posts: 948
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Re: Gas Guage Prob's
Ill check tonight in the garage and see what happens
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