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

bad72c10 · 02-06-2007, 05:37 PM

Okay, I know there is a bunch of other threads on right now, but here is my trouble. I took the wire off, and the guage went full, but when I hooked it back on, it went empty. Help here, I'm not sure what the problem is. Thanks, Justin

69TowRig · 02-06-2007, 06:42 PM

I'm betting it is a sunk float. I pulled mine off and found a hairline crack in it. Drilled out the solder in the end, soldered the crack then soldered the plug back in. Works good as new, and better than paying $6 - $9 plus shipping.

byrd · 02-06-2007, 07:30 PM

Bad float/sending unit

bad72c10 · 02-06-2007, 08:05 PM

Well I'm guessing a negative on the sunk float or bad sending unit, cause it i BRAND NEW. But I guess it's a possibility. Any others? Thanks, Justin

**VetteVet** · 02-06-2007, 08:14 PM

This may be some help.

http://www.6066gmcguy.org/Electrical-02.htm

brak · 02-06-2007, 08:36 PM

are you using the factory gauge?
If i understand correctly, it's a new sending unit?

you could check the resistance on the sending unit to verify that it is correct.
if using an aftermarket gauge, verify to make sure you have the correct one, as gm used a couple different styles of electrical metering, and a mismatch can cause a false reading.

Was that clear?

bad72c10 · 02-06-2007, 08:42 PM

Ya, that's clear brak, but it is the original gauge, and it is a brand new sending unit. Like I said, I took the wire off with the key on, and the gauge went to full. I put it back on, and it went to empty. Is it a bad ground, or what? I'm going to check the wire soon for any damage to it.

byrd · 02-06-2007, 09:02 PM

You do not hook it back up for the second half of the test you are to ground out the wire turn the ignition on and the gauge should read past empty. if that checks out then you have an issues with the sending unit itself

69TowRig · 02-06-2007, 09:55 PM

Grab an ohmmeter and check the resistance to ground on the wire coming into the cab (unplugged from the sender), then check the resistance to ground out at the sender. If the sender shows a resistance but the wire doesn't (or is really low) then the wire has a short to ground somewhere along it's length. A bad ground at the sender would show over full on the gas gauge.

02-06-2007, 05:37 PM	#1
bad72c10 Registered User Join Date: Dec 2006 Location: New Mexico Posts: 88	Gas Gauge Okay, I know there is a bunch of other threads on right now, but here is my trouble. I took the wire off, and the guage went full, but when I hooked it back on, it went empty. Help here, I'm not sure what the problem is. Thanks, Justin __________________ '72 C/10 SWB 355/ broken TH350 and 3.07s Soon to be 355/700r4 and 3.73s

02-06-2007, 06:42 PM	#2
69TowRig Senior Member Join Date: Jan 2005 Location: Raleigh, NC Posts: 894	Re: Gas Gauge I'm betting it is a sunk float. I pulled mine off and found a hairline crack in it. Drilled out the solder in the end, soldered the crack then soldered the plug back in. Works good as new, and better than paying $6 - $9 plus shipping. __________________ -Chris Building a stripper, one part at a time: 1969 K5, 307, 3spd, 3 seats, hard top. Added Pwr Discs, Pwr Steering, Aux Battery, T-case Skid, Lighted Sidemarkers, HEI, Lock-Right Diff, ECE Class IV Hitch, 32" MT/Rs. Parts to Install: Hand Throttle, Console, Tow Hooks, Dual Horns, AM-FM, Dealer Swing-Away Tire Carrier, Gas Tank Skid. Also building a 1950 Willys CJ-3A and off-roading a 2001 Nissan Frontier on 1-Ton Portals...

02-06-2007, 08:05 PM	#4
bad72c10 Registered User Join Date: Dec 2006 Location: New Mexico Posts: 88	Re: Gas Gauge Well I'm guessing a negative on the sunk float or bad sending unit, cause it i BRAND NEW. But I guess it's a possibility. Any others? Thanks, Justin __________________ '72 C/10 SWB 355/ broken TH350 and 3.07s Soon to be 355/700r4 and 3.73s

02-06-2007, 08:14 PM	#5
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,719	Re: Gas Gauge This may be some help. http://www.6066gmcguy.org/Electrical-02.htm __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

02-06-2007, 08:36 PM	#6
brak Registered User Join Date: Apr 2006 Location: MinneSNOWta Posts: 1,381	Re: Gas Gauge are you using the factory gauge? If i understand correctly, it's a new sending unit? you could check the resistance on the sending unit to verify that it is correct. if using an aftermarket gauge, verify to make sure you have the correct one, as gm used a couple different styles of electrical metering, and a mismatch can cause a false reading. Was that clear? __________________ 2003 GMC Sierra 1500 WT 1995 Nissan Hardbody 2016 Hyundai Veloster Turbo DC2 (SW/AW) Clyde W. Harvey USN "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery" Winston Churchill

02-06-2007, 08:42 PM	#7
bad72c10 Registered User Join Date: Dec 2006 Location: New Mexico Posts: 88	Re: Gas Gauge Ya, that's clear brak, but it is the original gauge, and it is a brand new sending unit. Like I said, I took the wire off with the key on, and the gauge went to full. I put it back on, and it went to empty. Is it a bad ground, or what? I'm going to check the wire soon for any damage to it. __________________ '72 C/10 SWB 355/ broken TH350 and 3.07s Soon to be 355/700r4 and 3.73s

02-06-2007, 09:55 PM	#9
69TowRig Senior Member Join Date: Jan 2005 Location: Raleigh, NC Posts: 894	Re: Gas Gauge Grab an ohmmeter and check the resistance to ground on the wire coming into the cab (unplugged from the sender), then check the resistance to ground out at the sender. If the sender shows a resistance but the wire doesn't (or is really low) then the wire has a short to ground somewhere along it's length. A bad ground at the sender would show over full on the gas gauge. __________________ -Chris Building a stripper, one part at a time: 1969 K5, 307, 3spd, 3 seats, hard top. Added Pwr Discs, Pwr Steering, Aux Battery, T-case Skid, Lighted Sidemarkers, HEI, Lock-Right Diff, ECE Class IV Hitch, 32" MT/Rs. Parts to Install: Hand Throttle, Console, Tow Hooks, Dual Horns, AM-FM, Dealer Swing-Away Tire Carrier, Gas Tank Skid. Also building a 1950 Willys CJ-3A and off-roading a 2001 Nissan Frontier on 1-Ton Portals... Last edited by 69TowRig; 02-06-2007 at 09:57 PM.

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