Gas Gauge / Sending Unit question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kxmotox247 · 08-26-2004, 01:12 PM

When your gas gauge doesn't work...the needle never moves from the same spot...is it always the sending unit? Or can it be the gauge?
What's the best way to test this? Any tips or suggestions would be appreciated!
Thanks,
Josh

grayw0lf · 08-26-2004, 01:57 PM

Play w/ the back of the gauge & 2 wires. One 12v+ & one 12v-. Touching the 2 poles should peg the gauge one way of the other.

Correct me if I'm wrong.

Old Dave · 08-26-2004, 03:00 PM

One side of your fuel gauge in the dash has +12 VDC connected to it. The sending unit in the tank is a variable resistor and when the tank is full it should read about 90 Ohms. When the tank is empty it should read close to 0 ohms. Check the brown wire that goes from the fuse panel to the sending unit in the tank to see if it's grounded under the sill plate along the drivers side door. If the wire checks out OK, try removing the sending unit from the tank and check it with an Ohmeter. The resistance should be about 90 Ohms when the float is up and almost 0 when the float is down. Check your float to see if it has a hole in it also. Hope this helps.

Bill72BB · 08-26-2004, 03:23 PM

What Old Dave said . and if the gauge reads past Full the brown wire is open or not connected to the sending unit .

kxmotox247 · 08-26-2004, 03:32 PM

Thanks to all of you. Both of my trucks have this problem and I'm tired of wondering how much is in there. One of these days it's going to bite me or my girlfriend.
Thanks for the info. I wish the search function was working properly because I hate asking questions that have probably been answered already.
Thanks again!

grayw0lf · 08-26-2004, 05:21 PM

Good answers!

08-26-2004, 01:12 PM	#1
kxmotox247 Senior Member Join Date: Jul 2002 Location: Champaign, IL Posts: 1,397	Gas Gauge / Sending Unit question When your gas gauge doesn't work...the needle never moves from the same spot...is it always the sending unit? Or can it be the gauge? What's the best way to test this? Any tips or suggestions would be appreciated! Thanks, Josh __________________ Baby Blue's Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=652776 Project 68's Build Thread: http://67-72chevytrucks.com/vboard/s...17#post8442117 www.stonecolumnclassics.com Email: Josh@stonecolumnclassics.com

08-26-2004, 01:57 PM	#2
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	Play w/ the back of the gauge & 2 wires. One 12v+ & one 12v-. Touching the 2 poles should peg the gauge one way of the other. Correct me if I'm wrong. __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

08-26-2004, 03:00 PM	#3
Old Dave Is a bullfrog waterproof? Join Date: Nov 2000 Location: OLATHE, KANSAS Posts: 1,130	One side of your fuel gauge in the dash has +12 VDC connected to it. The sending unit in the tank is a variable resistor and when the tank is full it should read about 90 Ohms. When the tank is empty it should read close to 0 ohms. Check the brown wire that goes from the fuse panel to the sending unit in the tank to see if it's grounded under the sill plate along the drivers side door. If the wire checks out OK, try removing the sending unit from the tank and check it with an Ohmeter. The resistance should be about 90 Ohms when the float is up and almost 0 when the float is down. Check your float to see if it has a hole in it also. Hope this helps. __________________ "It is better to remain silent and be thought a fool, than to open one's mouth and remove all doubt." Ben Franklin __________________ 1970 Chevy shortbed 2002 Harley Custom Chopper (Long sucker) 1998 K2500 5.7L 5-speed Longbed 1st two are My son's toys...they just live in my garage! 1997 GMC K1500 Suburban 1993 S-10 Blazer 4D (youngest son's daily driver) 2000 Dodge Ram 4WD Ext. Cab (5.9L) Wife is a late year 1951

08-26-2004, 03:23 PM	#4
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,979	What Old Dave said . and if the gauge reads past Full the brown wire is open or not connected to the sending unit . __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

08-26-2004, 03:32 PM	#5
kxmotox247 Senior Member Join Date: Jul 2002 Location: Champaign, IL Posts: 1,397	Thanks to all of you. Both of my trucks have this problem and I'm tired of wondering how much is in there. One of these days it's going to bite me or my girlfriend. Thanks for the info. I wish the search function was working properly because I hate asking questions that have probably been answered already. Thanks again! __________________ Baby Blue's Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=652776 Project 68's Build Thread: http://67-72chevytrucks.com/vboard/s...17#post8442117 www.stonecolumnclassics.com Email: Josh@stonecolumnclassics.com

08-26-2004, 05:21 PM	#6
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	Good answers! __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

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