fuel gauge wiring

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fuel gauge wiring

Postby beakerztoyz » Sun Sep 28, 2014 10:54 am

I fired up my car for the first time in a long time last night, anyways the fuel gauge is messed up somehow it always reads overfull when the powers on. it doesnt have that much gas in it we tested the wires in the trunk where the ones coming up from the tank join with the ones going to the front with a testlight, and somehow when we had the wires together and were testing with the light the gauge started reading acurately, took light out it went back up to overfull

anyone got any ideas on how to fix this or whats causing it?

trying one last time to get this car street legal so shit like this has to work asap thanks
1980 notchback sunbird... 355
1980 monza spyder.... v8

If I woulda known then what I know now....I never woulda got an h body
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beakerztoyz
 
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1980 Pontiac Sunbird


Re: fuel gauge wiring

Postby spencerforhire » Sun Sep 28, 2014 12:27 pm

The gauge works as a variable ground; you could be missing the ground wire if that was the one you touched with the test light. Or if you touch the tan gauge wire with it, that will bring it down too. Open circuit, gauge goes up past full. Shorted yo ground or empty, the gauge goes down.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- spare
and 3 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

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Re: fuel gauge wiring

Postby beakerztoyz » Sun Sep 28, 2014 1:28 pm

Thanks Spencer, so if i follow you correctly you think it's not grounded?
1980 notchback sunbird... 355
1980 monza spyder.... v8

If I woulda known then what I know now....I never woulda got an h body
User avatar
beakerztoyz
 
Posts: 337
Joined: Sun Feb 18, 2007 1:02 pm
Location: southern alberta

1980 Pontiac Sunbird

Re: fuel gauge wiring

Postby spencerforhire » Sun Sep 28, 2014 3:25 pm

Could be, but then the fuel pump probably wouldn't run. Try again with the test light and see which wire makes it go down.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- spare
and 3 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
User avatar
spencerforhire
 
Posts: 2442
Joined: Mon Jul 03, 2006 9:02 pm
Location: Halifax, Nova Scotia

1972 Chevrolet Vega Hatchback

Re: fuel gauge wiring

Postby beakerztoyz » Sun Sep 28, 2014 3:39 pm

ok thanks man I will recheck it, I didn't think to post in my first question that i am not running the in tank fuel pump, i have a holley electric one wired up externally.. on edit it is the tan wire i am hitting with the test light that is making it go down, so i am thinking that means its a short between that connector in the trunk and the tank ??
1980 notchback sunbird... 355
1980 monza spyder.... v8

If I woulda known then what I know now....I never woulda got an h body
User avatar
beakerztoyz
 
Posts: 337
Joined: Sun Feb 18, 2007 1:02 pm
Location: southern alberta

1980 Pontiac Sunbird

Re: fuel gauge wiring

Postby beakerztoyz » Sun Oct 05, 2014 11:37 pm

Just to update this, thanks to the wiring diagrams posted on this site i was able to trace the problem to an unhooked ground wire under the dash, i hooked it up and now the gauge works.. also thanks to Spencerforhire for the advice :)
1980 notchback sunbird... 355
1980 monza spyder.... v8

If I woulda known then what I know now....I never woulda got an h body
User avatar
beakerztoyz
 
Posts: 337
Joined: Sun Feb 18, 2007 1:02 pm
Location: southern alberta

1980 Pontiac Sunbird


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