Gas Gauge issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DoobieBrother · 08-30-2006, 11:52 PM

Hello. New to the board. Just getting started on a `68 C10 handed down a couple of generations and needs a load of work.

Ok trying to fix the gas guage on this `68 C10. Father in law told me it needed a new float when I picked it up from him. I ordered one and this evening went about installing it. When I pulled out the old sending unit, all looked pristine including the little bag. I think maybe he already replaced it once. At any rate I decided to pull off the old float even though it looked fine. When I pulled it off I noticed it was heavy. So, I'm thinking ok, maybe it's waterlogged. Decided to put the new obviously light and hollow one on and just for curiosity sake float the old one in the sink. Old one sank except one corner held it up. Ok, maybe bad.

So, I put the new one in and reinstalled. Hit the key, and nothing. Well, here's what I noticed. Needle sits near "Empty" label. When you hit the key, though, it moves maybe a 1/16 inch or so further to the left (empty side). Unplug the sending unit wire from fuse box, hit the key and it goes all the way over to full+. Like 3 o'clock position. So, I'm trying to figure out...Bad sending unit? Maybe somehow positioned wrong? What?

Thoughts?

jhow66 · 08-31-2006, 01:32 AM

Check here:
www.fix-a-gauge.com

jhow66 · 08-31-2006, 02:06 AM

This should help also:
http://www.6066gmcguy.org/Electrical-02.htm

68SHORTBOX · 08-31-2006, 02:17 AM

If you take the wire loose from the sender and ground it does the guage go to empty?? If the guage reads past full at the 3:00 position when you connect it the sending unit is bad. Check the back of the fuel guage in the dash ground the guage and see if it reads empty. If not guage is bad. This may help with trouble shooting.

GREASEMONKEY72 · 08-31-2006, 02:27 AM

is your tank still in the cab??? cuz mine would go to 3:00 position and then i grabed the wire and made contact again on the tank and its fine its only done that to me twice though but food for thought

LUV2XCLR8 · 08-31-2006, 06:19 PM

Quote:

Originally Posted by 68SHORTBOX

This may help with trouble shooting.

Do you have this in a larger version?, very handy to have

If so please E-mail to luv2xclr8@charter.net (Subject 67-72)

70c10 · 08-31-2006, 07:36 AM

If the new one reads empty it may have a bad float. The last sending unit I installed had a tiny break along the soldered joint and it was brand new. Take the new unit out and pop the float off and submerge it to see if it fills up or you see air bubbles. Just cuz it's new doesn't mean it's not defective. Good luck!

DoobieBrother · 08-31-2006, 01:33 PM

I got the following response on another board...

Quote:

Sounds like a bad sending unit to me or it's missing the ground wire on the tank bung (Tank bung the round dealie) Should have a positive wire from the dash to the bung and a ground wire from the bung attached to the frame. You may have the wires on the bung reversed.

I responded with...

Quote:

Doh! There's only one wire coming off the top of the sending unit. The positive. I was thinking the metal grommet made contact with the sending unit and the tank, and the tank was grounded by virtue of connection to the frame. Maybe that's it. Do you by chance have any pics I could check out?

I found this image...http://www.classicheartbeat.com/cata...ing%20Unit.htm

but I have no extra wire like that on the unit. I'll look tonight. I bet it's missing and I can add one in. I sure hope that's it.

...So, I'm thinking that may be it. Thoughts?

wydomkr · 08-31-2006, 05:36 PM

Dumb question, but how much gas is in the tank? I just replaced the sending unit on my 69, the tank had a bunch of crap in it, the sock was torn and the stem for the sender was plugged solid. When I put the replacement sender in, hit the key, it was still on empty. I thought crap, the used sender I had picked up was no good, but it looked like new. I went to the gas station, added gas and low and behold, it came up. It may not be 100% accurate, I don't know how much gas was in the tank to begin with, but it works. Mine only had the one wire for the power, no ground wire.

Keith

68SHORTBOX · 08-31-2006, 11:19 PM

Will enlarge it and PM to you.

08-30-2006, 11:52 PM	#1
DoobieBrother Registered User Join Date: Aug 2006 Location: US Posts: 184	Gas Gauge issues Hello. New to the board. Just getting started on a `68 C10 handed down a couple of generations and needs a load of work. Ok trying to fix the gas guage on this `68 C10. Father in law told me it needed a new float when I picked it up from him. I ordered one and this evening went about installing it. When I pulled out the old sending unit, all looked pristine including the little bag. I think maybe he already replaced it once. At any rate I decided to pull off the old float even though it looked fine. When I pulled it off I noticed it was heavy. So, I'm thinking ok, maybe it's waterlogged. Decided to put the new obviously light and hollow one on and just for curiosity sake float the old one in the sink. Old one sank except one corner held it up. Ok, maybe bad. So, I put the new one in and reinstalled. Hit the key, and nothing. Well, here's what I noticed. Needle sits near "Empty" label. When you hit the key, though, it moves maybe a 1/16 inch or so further to the left (empty side). Unplug the sending unit wire from fuse box, hit the key and it goes all the way over to full+. Like 3 o'clock position. So, I'm trying to figure out...Bad sending unit? Maybe somehow positioned wrong? What? Thoughts?

08-31-2006, 01:32 AM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Re: Gas Gauge issues Check here: www.fix-a-gauge.com __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

08-31-2006, 02:06 AM	#3
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Re: Gas Gauge issues This should help also: http://www.6066gmcguy.org/Electrical-02.htm __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

08-31-2006, 02:17 AM	#4
68SHORTBOX Registered User Join Date: Jul 2006 Location: El Cajon Ca Posts: 84	Re: Gas Gauge issues If you take the wire loose from the sender and ground it does the guage go to empty?? If the guage reads past full at the 3:00 position when you connect it the sending unit is bad. Check the back of the fuel guage in the dash ground the guage and see if it reads empty. If not guage is bad. This may help with trouble shooting. Last edited by 68SHORTBOX; 02-08-2007 at 08:43 PM.

08-31-2006, 02:27 AM	#5
GREASEMONKEY72 Registered User Join Date: Aug 2006 Location: Bakersfield,CA Posts: 7,893	Re: Gas Gauge issues is your tank still in the cab??? cuz mine would go to 3:00 position and then i grabed the wire and made contact again on the tank and its fine its only done that to me twice though but food for thought __________________ -steven Alte Seele S.S. "Allison" '72 C/10 LWB 350SB/TH350 - DD PITBULL IS NOT A CRIME

08-31-2006, 07:36 AM	#7
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	Re: Gas Gauge issues If the new one reads empty it may have a bad float. The last sending unit I installed had a tiny break along the soldered joint and it was brand new. Take the new unit out and pop the float off and submerge it to see if it fills up or you see air bubbles. Just cuz it's new doesn't mean it's not defective. Good luck! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

08-31-2006, 05:36 PM	#9
wydomkr Registered User Join Date: Mar 2006 Location: Rapid City, SD Posts: 96	Re: Gas Gauge issues Dumb question, but how much gas is in the tank? I just replaced the sending unit on my 69, the tank had a bunch of crap in it, the sock was torn and the stem for the sender was plugged solid. When I put the replacement sender in, hit the key, it was still on empty. I thought crap, the used sender I had picked up was no good, but it looked like new. I went to the gas station, added gas and low and behold, it came up. It may not be 100% accurate, I don't know how much gas was in the tank to begin with, but it works. Mine only had the one wire for the power, no ground wire. Keith __________________ Keith ------------- 1980 C-10 1981 C-30

08-31-2006, 11:19 PM	#10
68SHORTBOX Registered User Join Date: Jul 2006 Location: El Cajon Ca Posts: 84	Re: Gas Gauge issues Will enlarge it and PM to you. Last edited by 68SHORTBOX; 09-01-2006 at 12:11 AM.



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