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

Bluehealercsf · 05-10-2010, 06:27 PM

Quick question, I just replaced my gas tank/all fuel lines/sending unit in my 72. Filled up the tank and I am reading 1/8 shy of full, do I need to just bend the sending unit arm till correct? It was reading dead on empty after install.

sameyrasmea72 · 05-10-2010, 08:33 PM

I would not bend anything.If the difference is on the full side it would not bother me. It’s the EEEEEEEEEEEE side that worries me. I would watch it and if E is empty then that ain’t bad for a 40 year old gauge. I tried to get mine perfect and went through 2 s-units and 4 gauges trying to move the needles and recalibrate them. But my problem was on the EMPTY SIDE. Finally the fifth gauge worked.

**VetteVet** · 05-10-2010, 08:45 PM

Pull the sender out and with the tan wire hooked to the sender and the key on. Ground the sender flange and raise the float arm up and down and watch the fuel gauge to see if it reads full or slightly over when you lift the arm all the way up. If it reads where you want it to then bend the float arm down slightly and it should read full when the gas is full in the tank. If you can, get a voltmeter and read the ohms from full to empty KEY OFF. Should read 0 to 90 ohms.

Most vehicles will read full for a long time then start dropping quickly as the fuel starts letting the float drop. Keep in mind that you will have less in reserve as the gauge gets to empty.

gonzo6869 · 05-10-2010, 08:48 PM

I have the same problem with mine, but it is not a 1/8 its more like a 1/16 off at full. I know its not much, but it bugs me

. Did you have any problems installing the sending unit? The one I got seem to be to long and was hitting the bottom of the tank, I had to bend it just a little for it to fit in.

Bluehealercsf · 05-11-2010, 12:22 AM

Mine installed no problem and was reading on Empty when I turned key on, I put in about 2 gallons to get to the gas station and it read about 1/16 above E. When I filled it at the station it read 1/8 shy of full, not that big of a deal but it just bothers me. I will remove it and check full travel with it hooked up like I should have done before install and then try a slight bend to correct.

Legolas894 · 05-11-2010, 08:10 PM

These things are a pain and I guess it's like VetteVet said, "It's a 40 year old gauge". I ran out of gas on Saturday with the gauge reading 1/4 and when it's full it's way past full.

That's what you call "character"!

**slomotion** · 05-11-2010, 08:36 PM

Bending the float arm down just a dite will correct it. Having said that, I personally would rather have the extra gallon or so on the "E" side. If my wife were ever driving the truck I'd feel better knowing when the tank got close to empty she'd have a reserve even if she didn't know it. (Because I wouldn't tell her. If I did, she'd ride on the reserve before she put gas in it.

)

Bluehealercsf · 05-11-2010, 08:50 PM

Thanks for all the info, I took it out last night and gave it a slight bend. It now reads a needle width away from full so I am perfectlly content with that, it did take me twice to remove bend and reinstall, I like the idea of it not going past full so I do have a little in the tank after empty.

05-10-2010, 06:27 PM	#1
Bluehealercsf Registered User Join Date: Jan 2008 Location: Abilene, Texas Posts: 24	Sending Unit Quick question, I just replaced my gas tank/all fuel lines/sending unit in my 72. Filled up the tank and I am reading 1/8 shy of full, do I need to just bend the sending unit arm till correct? It was reading dead on empty after install. __________________ __________________ 72 CHEVROLET K/10 4X4 05 CHEVROLET 2500HD

05-10-2010, 08:33 PM	#2
sameyrasmea72 Senior Member Join Date: Aug 2003 Location: Lubbock, Texas Posts: 2,443	Re: Sending Unit I would not bend anything.If the difference is on the full side it would not bother me. It’s the EEEEEEEEEEEE side that worries me. I would watch it and if E is empty then that ain’t bad for a 40 year old gauge. I tried to get mine perfect and went through 2 s-units and 4 gauges trying to move the needles and recalibrate them. But my problem was on the EMPTY SIDE. Finally the fifth gauge worked. __________________ 72 Cheyenne Super 80 Silverado Blazer 2wd

05-10-2010, 08:45 PM	#3
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,719	Re: Sending Unit Pull the sender out and with the tan wire hooked to the sender and the key on. Ground the sender flange and raise the float arm up and down and watch the fuel gauge to see if it reads full or slightly over when you lift the arm all the way up. If it reads where you want it to then bend the float arm down slightly and it should read full when the gas is full in the tank. If you can, get a voltmeter and read the ohms from full to empty KEY OFF. Should read 0 to 90 ohms. Most vehicles will read full for a long time then start dropping quickly as the fuel starts letting the float drop. Keep in mind that you will have less in reserve as the gauge gets to empty. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

05-10-2010, 08:48 PM	#4
gonzo6869 Cops, ha, catch me if you can! Join Date: Jun 2009 Location: Santa Barbara, CA. Posts: 271	Re: Sending Unit I have the same problem with mine, but it is not a 1/8 its more like a 1/16 off at full. I know its not much, but it bugs me. Did you have any problems installing the sending unit? The one I got seem to be to long and was hitting the bottom of the tank, I had to bend it just a little for it to fit in. __________________ 72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies

05-11-2010, 12:22 AM	#5
Bluehealercsf Registered User Join Date: Jan 2008 Location: Abilene, Texas Posts: 24	Re: Sending Unit Mine installed no problem and was reading on Empty when I turned key on, I put in about 2 gallons to get to the gas station and it read about 1/16 above E. When I filled it at the station it read 1/8 shy of full, not that big of a deal but it just bothers me. I will remove it and check full travel with it hooked up like I should have done before install and then try a slight bend to correct. __________________ __________________ 72 CHEVROLET K/10 4X4 05 CHEVROLET 2500HD

05-11-2010, 08:10 PM	#6
Legolas894 Chemist under the hood... Join Date: Apr 2009 Location: Fort Erie,ON, Canada Posts: 617	Re: Sending Unit These things are a pain and I guess it's like VetteVet said, "It's a 40 year old gauge". I ran out of gas on Saturday with the gauge reading 1/4 and when it's full it's way past full. That's what you call "character"! __________________ Current fleet: 2013 GMC Sierra, 5.3L, 4x4 1988 GMC Sierra, 305, Auto 1984 Jeep Grand Wagoneer, 360 V8 1997 VW Cabrio, 2.0L 2017 Toyota Rav4, 2.5L Stuff I wish I still had: 2013 Toyota Matrix [RIP] 1967 GMC 910 Fleetside, 283 V8 [1st Love-SOLD] 1987 Jeep Cherokee Laredo 4X4, 4.0 I-6 [SOLD} 1994 Chevrolet Caprice Classic, 5.7LV8 [SOLD] 1995 Chevrolet Astro AWD, 4.3L V6 (RIP) 1998 Chevrolet Suburban 4x4, 5.7L V8 [SOLD]

05-11-2010, 08:36 PM	#7
slomotion Old Duffer Join Date: Mar 2003 Location: Maine Posts: 1,822	Re: Sending Unit Bending the float arm down just a dite will correct it. Having said that, I personally would rather have the extra gallon or so on the "E" side. If my wife were ever driving the truck I'd feel better knowing when the tank got close to empty she'd have a reserve even if she didn't know it. (Because I wouldn't tell her. If I did, she'd ride on the reserve before she put gas in it.) __________________ '68 Short C20 Flatbed Dually w/ 292 4bbl, Langdon cast headers, and WC T5 trans. '81 G10 Shorty Van "Good judgement comes from experience, and a lot of that comes from bad judgement." Will Rogers "Under promise, then over achieve."

05-11-2010, 08:50 PM	#8
Bluehealercsf Registered User Join Date: Jan 2008 Location: Abilene, Texas Posts: 24	Re: Sending Unit Thanks for all the info, I took it out last night and gave it a slight bend. It now reads a needle width away from full so I am perfectlly content with that, it did take me twice to remove bend and reinstall, I like the idea of it not going past full so I do have a little in the tank after empty. __________________ __________________ 72 CHEVROLET K/10 4X4 05 CHEVROLET 2500HD



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