fuel sending unit - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gmcpkup · 01-20-2009, 09:05 AM

I moved my gas tank to under the bed and with the aftermarket sending unit the stock gas gauge when empty still shows a 1/4 tank. Anyone have any info:

Joey~AP · 01-20-2009, 09:52 AM

Does your float move in the full range of the tank?

Are they compatible with each other? (tank/sending unit)

gmcpkup · 01-20-2009, 10:00 AM

I don't know if they are compatible or not I bought the truck as a basket case and the tank was with it.

TheDark1 · 01-20-2009, 12:33 PM

I had the same problem with a "Harwood" fuel cell. I bent the float rod on the sendind unit to get it where I wanted it

custom63 · 01-20-2009, 12:38 PM

Are you using your original gauges in the cab?

vin63 · 01-20-2009, 12:43 PM

More than likely, the fuel level sending unit in your new tank has a 0-90 ohm operation (late model GM). Unfortunately, your stock fuel level gauge requires a 0-30 ohm signal to function properly. You'll either need to switch to an aftermarket fuel level gauge with a 0-90 ohm operation, or try and find a 0-30 ohm resistor to replace the 0-90 ohm resistor on the sending unit...the former being much easier.

custom63 · 01-20-2009, 12:45 PM

Thats what I was thinkin.

TheDark1 · 01-20-2009, 12:49 PM

Mine were compatible, just not properly "adjusted". I do have the factory fuel gauge. I also remember tweaking the gauge needle a little also. It's a little fuzzy, since I did it about 15 years ago. I put it exactly on the empty line at the floats lowest point. That way I knew when it hit empty I was done for.

gmcpkup · 01-20-2009, 02:16 PM

I am using the stock gauge so maybe they are not compatible thanks for the imput. If any one knows where I can get different parts for the sending unit I would appreciate the info.

vin63 · 01-20-2009, 02:18 PM

Quote:

Originally Posted by gmcpkup

I am using the stock gauge so maybe they are not compatible thanks for the imput. If any one knows where I can get different parts for the sending unit I would appreciate the info.

Do you have a photo of your new sending unit? Particularly, the float level assembly?

TheDark1 · 01-20-2009, 02:23 PM

When you fill up the tank, does the gauge read full, or does it move at all?

*LILRED66* · 01-20-2009, 05:19 PM

Quote:

Originally Posted by gmcpkup

I am using the stock gauge so maybe they are not compatible thanks for the imput. If any one knows where I can get different parts for the sending unit I would appreciate the info.

Try these sites for parts for your truck, including fuel sending units:

www.bowtiebits.com
www.lmctruck.com
www.classicparts.com
www.ecklerstrucks.com
www.gspp.com
www.truckandcarshop.com
www.harmons.com
www.oldmusclecars.com
www.classicchevroletparts.com
www.classicindustries.com
www.bobschevytrucks.com
www.brotherstrucks.com
www.mar-k.com
www.wheelvintiques.com
www.totallystainless.com
www.earlyclassic.com
www.horkeyswoodandparts.com
www.raybuck.com
www.americanclassic.com
www.yogisinc.com
www.rbsauto.com
www.obschevy.com
www.cheyennepickup.com
www.chevypickupparts.com

Not all of these sites will have fuel sending units, but they are good sources for other items, as well.

gmcpkup · 01-20-2009, 10:20 PM

thanks for all the feed back the float system I have, is a float that slides up a tube not one that pivots like the original. Yes it does move to full when I fill it up but it stops at a 1/4 tank when it is empty. It seems as though it sit at 1/4 full a while before it is empty

ol Curt · 01-21-2009, 10:41 AM

Quote:

Originally Posted by vin63

More than likely, the fuel level sending unit in your new tank has a 0-90 ohm operation (late model GM). Unfortunately, your stock fuel level gauge requires a 0-30 ohm signal to function properly. You'll either need to switch to an aftermarket fuel level gauge with a 0-90 ohm operation, or try and find a 0-30 ohm resistor to replace the 0-90 ohm resistor on the sending unit...the former being much easier.

I'm not trying to be smart, but rather learn. I've never really paid too much attention to the sending units, but would like to put a tank in the rear but use my factory gauge. How difficult is it to change the resistor? I assume it is not like a regular one you could pick up at Radio Shack and solder in?

vin63 · 01-21-2009, 01:19 PM

Generally, it's not difficult to change. The difficult aspect is finding a 0-30 ohm resister that is the same shape and dimension. In my experience, often the type of resistor that is used for some of the fuel cell, or custom tank applications only is available in the 0-90 ohm range. There are components that you can splice into the wire harness, but I've never been able to get those to work very well.

71Farmtruck · 04-23-2009, 10:19 PM

Can anyone post up what the ohm ranges are from the factory between the different year models?

01-20-2009, 09:05 AM	#1
gmcpkup Registered User Join Date: May 2004 Location: west olive mi. Posts: 24	fuel sending unit I moved my gas tank to under the bed and with the aftermarket sending unit the stock gas gauge when empty still shows a 1/4 tank. Anyone have any info: Last edited by gmcpkup; 01-20-2009 at 09:06 AM.

01-20-2009, 09:52 AM	#2
Joey~AP TexasBowhunter Join Date: Mar 2008 Location: alvin, texas Posts: 450	Re: fuel sending unit Does your float move in the full range of the tank? Are they compatible with each other? (tank/sending unit) __________________ Build in progress for son's first truck.

01-20-2009, 10:00 AM	#3
gmcpkup Registered User Join Date: May 2004 Location: west olive mi. Posts: 24	Re: fuel sending unit I don't know if they are compatible or not I bought the truck as a basket case and the tank was with it.

01-20-2009, 12:33 PM	#4
TheDark1 Intentionally Left Blank Join Date: Dec 2008 Location: Broussard, LA Posts: 355	Re: fuel sending unit I had the same problem with a "Harwood" fuel cell. I bent the float rod on the sendind unit to get it where I wanted it __________________ 1965 C-10 Short Fleet 468/TKO 5-Speed 2004 2500HD Crew 496/Ally Blacked Out (SOLD!!) 1997 Formula WS6 2004 Jeep Wrangler (Sold) 2013 Jeep Wrangler (Sold) 2017 Jeep Wrangler (Blacked Out on 35's) 2011 GMC D-Max Dually Denali 3500HD (Sold) 2015 GMC D-Max Dually Denali 3500HD (Sold) 2018 GMC D-Max Dually Denali 3500HD (Sold) 2020 D-Max Dually Denali on 33x12.50's 1979 GMC Short Bed Step-Side 4x4 350/350 Low Miles

01-20-2009, 12:38 PM	#5
custom63 Registered User Join Date: Oct 2008 Location: Auburn, Ca. Posts: 171	Re: fuel sending unit Are you using your original gauges in the cab?

01-20-2009, 12:43 PM	#6
vin63 It's Better With Nitro Join Date: Apr 2008 Location: Chino Hills, CA Posts: 2,261	Re: fuel sending unit More than likely, the fuel level sending unit in your new tank has a 0-90 ohm operation (late model GM). Unfortunately, your stock fuel level gauge requires a 0-30 ohm signal to function properly. You'll either need to switch to an aftermarket fuel level gauge with a 0-90 ohm operation, or try and find a 0-30 ohm resistor to replace the 0-90 ohm resistor on the sending unit...the former being much easier. __________________ 1963 C-10: Deluxe-optioned cab, shortbed, fleetside Pontiac 462 ci, Kauffman D-Port alum. heads 4L80E, narrowed sheetmetal Ford 9-inch Tubular front and rear suspension Custom 6-piston front disc and 4-piston rear disc brakes

01-20-2009, 12:45 PM	#7
custom63 Registered User Join Date: Oct 2008 Location: Auburn, Ca. Posts: 171	Re: fuel sending unit Thats what I was thinkin.

01-20-2009, 12:49 PM	#8
TheDark1 Intentionally Left Blank Join Date: Dec 2008 Location: Broussard, LA Posts: 355	Re: fuel sending unit Mine were compatible, just not properly "adjusted". I do have the factory fuel gauge. I also remember tweaking the gauge needle a little also. It's a little fuzzy, since I did it about 15 years ago. I put it exactly on the empty line at the floats lowest point. That way I knew when it hit empty I was done for. __________________ 1965 C-10 Short Fleet 468/TKO 5-Speed 2004 2500HD Crew 496/Ally Blacked Out (SOLD!!) 1997 Formula WS6 2004 Jeep Wrangler (Sold) 2013 Jeep Wrangler (Sold) 2017 Jeep Wrangler (Blacked Out on 35's) 2011 GMC D-Max Dually Denali 3500HD (Sold) 2015 GMC D-Max Dually Denali 3500HD (Sold) 2018 GMC D-Max Dually Denali 3500HD (Sold) 2020 D-Max Dually Denali on 33x12.50's 1979 GMC Short Bed Step-Side 4x4 350/350 Low Miles

01-20-2009, 02:16 PM	#9
gmcpkup Registered User Join Date: May 2004 Location: west olive mi. Posts: 24	Re: fuel sending unit I am using the stock gauge so maybe they are not compatible thanks for the imput. If any one knows where I can get different parts for the sending unit I would appreciate the info.

01-20-2009, 02:23 PM	#11
TheDark1 Intentionally Left Blank Join Date: Dec 2008 Location: Broussard, LA Posts: 355	Re: fuel sending unit When you fill up the tank, does the gauge read full, or does it move at all? __________________ 1965 C-10 Short Fleet 468/TKO 5-Speed 2004 2500HD Crew 496/Ally Blacked Out (SOLD!!) 1997 Formula WS6 2004 Jeep Wrangler (Sold) 2013 Jeep Wrangler (Sold) 2017 Jeep Wrangler (Blacked Out on 35's) 2011 GMC D-Max Dually Denali 3500HD (Sold) 2015 GMC D-Max Dually Denali 3500HD (Sold) 2018 GMC D-Max Dually Denali 3500HD (Sold) 2020 D-Max Dually Denali on 33x12.50's 1979 GMC Short Bed Step-Side 4x4 350/350 Low Miles

01-20-2009, 10:20 PM	#13
gmcpkup Registered User Join Date: May 2004 Location: west olive mi. Posts: 24	Re: fuel sending unit thanks for all the feed back the float system I have, is a float that slides up a tube not one that pivots like the original. Yes it does move to full when I fill it up but it stops at a 1/4 tank when it is empty. It seems as though it sit at 1/4 full a while before it is empty

01-21-2009, 01:19 PM	#15
vin63 It's Better With Nitro Join Date: Apr 2008 Location: Chino Hills, CA Posts: 2,261	Re: fuel sending unit Generally, it's not difficult to change. The difficult aspect is finding a 0-30 ohm resister that is the same shape and dimension. In my experience, often the type of resistor that is used for some of the fuel cell, or custom tank applications only is available in the 0-90 ohm range. There are components that you can splice into the wire harness, but I've never been able to get those to work very well. __________________ 1963 C-10: Deluxe-optioned cab, shortbed, fleetside Pontiac 462 ci, Kauffman D-Port alum. heads 4L80E, narrowed sheetmetal Ford 9-inch Tubular front and rear suspension Custom 6-piston front disc and 4-piston rear disc brakes

04-23-2009, 10:19 PM	#16
71Farmtruck Junk Junkie Join Date: Oct 2007 Location: Humble, TX Posts: 123	Re: fuel sending unit Can anyone post up what the ohm ranges are from the factory between the different year models? __________________ Mike 71 Chevrolet C-10 Short Bed Stepside 81 GMC 1500 Sierra Classic Long Bed



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