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Author Topic: gas guage always reads full when ignition is on  (Read 8039 times)

Offline joakley22

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gas guage always reads full when ignition is on
« on: February 24, 2011, 01:36:51 pm »
I have a 73 chevy 2WD with a 78 cab on it. when me and my dad switched the old rusted out cab with the new 78 cab we think we didnt connect the gas guage correctly. all the other guages work perfectly fine is there any suggestions???
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Offline 87454westernhauler

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Re: gas guage always reads full when ignition is on
« Reply #1 on: February 24, 2011, 01:56:34 pm »
you probably didn't get the wire hooked up that runs the gage, if there is not power from the trank to the gage it will just read that it is full all of the time. I may be wrong, but that is my two cents worth!
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86 c10 350 sbc 700R4 Daily Driver
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Offline joakley22

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Re: gas guage always reads full when ignition is on
« Reply #2 on: February 24, 2011, 01:58:10 pm »
well... when the ignition is off it reads well above full but when i turn the ignition the needle goes right to the full mark so there is power to it.
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Offline txchainsawgogi

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Re: gas guage always reads full when ignition is on
« Reply #3 on: February 24, 2011, 03:55:03 pm »
did it ever work? faulty fuel gauges seem to be extremely common with these trucks...mine doesnt even work haha.
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Offline joakley22

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Re: gas guage always reads full when ignition is on
« Reply #4 on: February 24, 2011, 04:13:06 pm »
im not 100% sure cause we changed the cab before it was running so that could very well be it.
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Offline DnStClr

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Re: gas guage always reads full when ignition is on
« Reply #5 on: February 24, 2011, 05:52:18 pm »
There have been a bunch of posts about fuel gauge problems. Do a search for "fuel gauge past full", or something similar and you might find one that's similar to help you get started troubleshooting. One of the guys, Lorne, posted this one in the technical section- he figured out how to troubleshoot the gauge using an old headlight switch...
http://forum.73-87chevytrucks.com/smforum/index.php?topic=16071.0
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Don
87 Chevy Silverado

Offline 4x4orbust

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Re: gas guage always reads full when ignition is on
« Reply #6 on: February 24, 2011, 05:55:58 pm »
i had the same problem as you.  I put in a new sending unit and checked for power at the gauge, all checked out ok.   the next day i did some welding on the truck, and now it works, kinda.   full is past full on the gauge (about 1/4"), and empty is just below 3/4 full.  ??? ??? ???

no idea why these trucks like to run out of gas, but they always are trying to make it happen!!
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1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline 77 cc lb

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Re: gas guage always reads full when ignition is on
« Reply #7 on: February 25, 2011, 12:05:17 pm »
do you happen to have dual tanks? the switch on mine got pushed down to the left tank (which i don't use) and caused the fuel gauge to read the way past full mark. flipped it back to right side and was back to normal.
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87 Chevy crewcab shortbed soon to have a 454/400

Offline roger97338

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Re: gas guage always reads full when ignition is on
« Reply #8 on: February 26, 2011, 04:48:27 am »
You might have the magic, always-full gas tank that the genie promised to me!
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Offline VileZambonie

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Re: gas guage always reads full when ignition is on
« Reply #9 on: February 26, 2011, 06:32:34 am »
Turn key on, remove wire from sending unit at tank (pink) and ground the wire. Observe gauge response and report.
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