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

charles oliver · 07-28-2003, 02:02 PM

I replaced Gas Gauge sending unit and it doesn't have a place for a ground, the original didn't either. It doesn't work any ideas on how to ground it.
68 Chevy C10 Short bed stepside

lukecp · 07-28-2003, 02:07 PM

The sending unit shouldn't be grounded. If it is grounded out, the guage will go way past full and not work.

bpmcgee · 07-28-2003, 02:42 PM

72,

I have to disagree with you. The sending unit MUST be grounded. It takes two wires to make a circuit, and there's only a brown wire coming from the guage.

Sending units are usually grounded via the tank. When I switched to a poly tank, I had to create a separate ground by running a grounding strap from one of the screws on the flange to the body.

If your tank is metal, you need to make sure that you have a good clean metal all the way from the sending unit to the frame. Alternately, you can jam a spade terminal between the sending unit and the locking ring, then run a wire from there to the frame.

Brian

lukecp · 07-28-2003, 02:49 PM

You are right, but there isn't a ground wire to the sending unit. That is what i was refering to. It should be grounded through the tank, assuming charle oliver has a original metal thank, there is no need for a ground wire. The tank is attached in about 4 places to the frame, so unless it is really corroded, it should work.

charles oliver · 07-28-2003, 04:26 PM

I am having a problem with understanding how the sending unit is grounded to the tank. There is a rubber O ring that separates the sending unit from the tank. I have tried 4 different gas gauges and none work. If I remove the wire to the fuse block it registers way past full. When I hook it back up it goes to empty and there is plenty of gas in it. This was also true before I replaced the tank sending unit. Any other ideas ?
Thanks
Charlie

lukecp · 07-28-2003, 06:59 PM

If it goes to empty after hooking the wire back up, the float on the gas tank may be full of gas, or it fell off. Pull the sending unit and see what it looks like.

Bill72BB · 07-28-2003, 07:06 PM

charles oliver
You said you removed the wire at the fuse block and it went past full ,
Now remove the wire at the sending unit if it goes past full again them the problem is with the sending unit or float.
If it stays on Empty the wire is grounded , replace it and that should fix the problem.

71GMC_3/4T · 07-28-2003, 08:10 PM

Yep, I was going to say that too. I'll be the brown wire is pinched by the seat, trim, or gas tank.

mtdave2 · 07-28-2003, 09:03 PM

after you put the unit in the tank, you put on a metal ring to hold it in. that is what is making the ground. you have a bad spot in the wire someplace.

charles oliver · 08-04-2003, 06:03 PM

You were absolutely right. The wire was pinched where I couldn't see it.
Thanks
Charlie

07-28-2003, 02:02 PM	#1
charles oliver 68 camtruck Join Date: Mar 2000 Location: Harrison, Ohio USA Posts: 233	Gas Gauge Sending Unit I replaced Gas Gauge sending unit and it doesn't have a place for a ground, the original didn't either. It doesn't work any ideas on how to ground it. 68 Chevy C10 Short bed stepside

07-28-2003, 02:07 PM	#2
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	The sending unit shouldn't be grounded. If it is grounded out, the guage will go way past full and not work. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

07-28-2003, 02:49 PM	#4
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	You are right, but there isn't a ground wire to the sending unit. That is what i was refering to. It should be grounded through the tank, assuming charle oliver has a original metal thank, there is no need for a ground wire. The tank is attached in about 4 places to the frame, so unless it is really corroded, it should work. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

07-28-2003, 04:26 PM	#5
charles oliver 68 camtruck Join Date: Mar 2000 Location: Harrison, Ohio USA Posts: 233	I am having a problem with understanding how the sending unit is grounded to the tank. There is a rubber O ring that separates the sending unit from the tank. I have tried 4 different gas gauges and none work. If I remove the wire to the fuse block it registers way past full. When I hook it back up it goes to empty and there is plenty of gas in it. This was also true before I replaced the tank sending unit. Any other ideas ? Thanks Charlie __________________ 71 GMC Jimmy 4X4 68 Huger Orange Camaro 454 with TH400 :gmc:

07-28-2003, 06:59 PM	#6
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	If it goes to empty after hooking the wire back up, the float on the gas tank may be full of gas, or it fell off. Pull the sending unit and see what it looks like. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

07-28-2003, 02:42 PM	#3
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	72, I have to disagree with you. The sending unit MUST be grounded. It takes two wires to make a circuit, and there's only a brown wire coming from the guage. Sending units are usually grounded via the tank. When I switched to a poly tank, I had to create a separate ground by running a grounding strap from one of the screws on the flange to the body. If your tank is metal, you need to make sure that you have a good clean metal all the way from the sending unit to the frame. Alternately, you can jam a spade terminal between the sending unit and the locking ring, then run a wire from there to the frame. Brian

07-28-2003, 07:06 PM	#7
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,979	charles oliver You said you removed the wire at the fuse block and it went past full , Now remove the wire at the sending unit if it goes past full again them the problem is with the sending unit or float. If it stays on Empty the wire is grounded , replace it and that should fix the problem. __________________ 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 ,

07-28-2003, 08:10 PM	#8
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	Yep, I was going to say that too. I'll be the brown wire is pinched by the seat, trim, or gas tank. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

07-28-2003, 09:03 PM	#9
mtdave2 newly minted old timer Join Date: Dec 1999 Location: Hudson WI Posts: 3,521	after you put the unit in the tank, you put on a metal ring to hold it in. that is what is making the ground. you have a bad spot in the wire someplace. __________________ ____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban

08-04-2003, 06:03 PM	#10
charles oliver 68 camtruck Join Date: Mar 2000 Location: Harrison, Ohio USA Posts: 233	You were absolutely right. The wire was pinched where I couldn't see it. Thanks Charlie

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