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GAS TANK SENDING UNIT ADJUSTMENT #1469695 07/18/13 10:13 AM 07/18/13 10:13 AM
Joined: Apr 2009 Posts: 43 Michigan A AnRT4Me OP member
AnRT4Me OP member A Joined: Apr 2009 Posts: 43 Michigan	Can anyone please tell me how to adjust the gas tank sending unit in my 1970 Dodge Coronet RT. I installed a new unit a while back and when I fill the car up, my fuel gauge only shows a little less than 3/4 of a tank. I know the fuel gauge is accurate, as I had send my complete gauge cluster to Redline Instruments, and it is dead on. I have a good ground connection to the sending unit, so I know this is not the problem, or is it? Thanks for any and all replies.

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: AnRT4Me] #1469696 07/18/13 10:19 AM 07/18/13 10:19 AM
Joined: Apr 2010 Posts: 4,154 bethlehem pa M mikemee1331 master
mikemee1331 master M Joined: Apr 2010 Posts: 4,154 bethlehem pa	i'll jump on this before the flames start. there is no one fix or good fix for this problem. just about everyone who has bought an aftermarket repop has this issue. my suggestion is to do a search (at the top of the page) and see what others have been doing. in most cases, they're living with it. sorry.

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: mikemee1331] #1469697 07/18/13 10:22 AM 07/18/13 10:22 AM
Joined: Apr 2006 Posts: 3,675 Akron, Ohio U.S.A. roadhazard master
roadhazard master Joined: Apr 2006 Posts: 3,675 Akron, Ohio U.S.A.	I bought one for my '71 B body from Mancini and it works just fine. Am I just lucky

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: roadhazard] #1469698 07/18/13 11:01 AM 07/18/13 11:01 AM
Joined: Jan 2007 Posts: 1,032 Ohio dobie super stock
dobie super stock Joined: Jan 2007 Posts: 1,032 Ohio	Quote: I bought one for my '71 B body from Mancini and it works just fine. Am I just lucky Maybe. I've tried three now, from separate vendors and all have been WAY off. On a full tank the gauge reads 3/4, then drops quickly to "E" on a 1/2 or a bit more. I'd be willing to spend the money (again) just to get one that works. P.S. I see we're neighbors.. Last edited by dobie; 07/18/13 11:01 AM. 1968 Plymouth Road Runner 383 4 speed

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: dobie] #1469699 07/18/13 11:59 AM 07/18/13 11:59 AM
Joined: Apr 2006 Posts: 3,675 Akron, Ohio U.S.A. roadhazard master
roadhazard master Joined: Apr 2006 Posts: 3,675 Akron, Ohio U.S.A.	Quote: Quote: I bought one for my '71 B body from Mancini and it works just fine. Am I just lucky Maybe. I've tried three now, from separate vendors and all have been WAY off. On a full tank the gauge reads 3/4, then drops quickly to "E" on a 1/2 or a bit more. I'd be willing to spend the money (again) just to get one that works. P.S. I see we're neighbors.. Yes neighbors we may just have to get together for a sometime Well luck for you there is a shop in Akron called S U R & R on S. Main Street that specializes in fuel sending units. Bet if you take one over there they can get your unit figured out

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: roadhazard] #1469700 07/18/13 12:48 PM 07/18/13 12:48 PM
Joined: Jan 2007 Posts: 1,032 Ohio dobie super stock
dobie super stock Joined: Jan 2007 Posts: 1,032 Ohio	Quote: Quote: Quote: I bought one for my '71 B body from Mancini and it works just fine. Am I just lucky Maybe. I've tried three now, from separate vendors and all have been WAY off. On a full tank the gauge reads 3/4, then drops quickly to "E" on a 1/2 or a bit more. I'd be willing to spend the money (again) just to get one that works. P.S. I see we're neighbors.. Yes neighbors we may just have to get together for a sometime Well luck for you there is a shop in Akron called S U R & R on S. Main Street that specializes in fuel sending units. Bet if you take one over there they can get your unit figured out Sounds good!! Thanks for the shop info. I'll definitely be checking them out! 1968 Plymouth Road Runner 383 4 speed

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: dobie] #1469701 07/18/13 01:04 PM 07/18/13 01:04 PM
Joined: May 2003 Posts: 1,751 Graham, WA P Polarapete top fuel
Polarapete top fuel P Joined: May 2003 Posts: 1,751 Graham, WA	Correct me if I am wrong, but if the float would go through it's full range of motion as the tank is filled it should read correctly? Ore is there more to it? 1986 Dodge Ramcharger 440 2wd, Bracket Racer Under Construction 1998 Ram 2500 QuadCab, new daily driver. 2008 Honda Element 2014 Carry-On 7x14 Cargo Trailer

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Polarapete] #1469702 07/18/13 01:59 PM 07/18/13 01:59 PM
Joined: Aug 2010 Posts: 343 S.E.Mich D drew72 enthusiast
drew72 enthusiast D Joined: Aug 2010 Posts: 343 S.E.Mich	Quote: Correct me if I am wrong, but if the float would go through it's full range of motion as the tank is filled it should read correctly? Ore is there more to it? You're correct. I guess some people don't know how to adjust (bend) the float arm. The gauge drops quickly after hitting 1/2 way because the float arm needs to be tweaked down a little bit. Some trial and error is sometimes needed, but they work in the end.

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: drew72] #1469703 07/18/13 02:16 PM 07/18/13 02:16 PM
Joined: Jan 2007 Posts: 1,032 Ohio dobie super stock
dobie super stock Joined: Jan 2007 Posts: 1,032 Ohio	Well, I've tried bending the arm in both directions. Still they've never been right. 1968 Plymouth Road Runner 383 4 speed

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: dobie] #1469704 07/18/13 03:02 PM 07/18/13 03:02 PM
Joined: Nov 2003 Posts: 1,029 Southeast Virginia 68jim super stock
68jim super stock Joined: Nov 2003 Posts: 1,029 Southeast Virginia	I would imagine that your 70 Dodge tank is roughly the same as my 68 Plymouth B-body tank. When I got my repro sender I did a side-by-side comparison and found that the arm was a bit longer on the repro sender. When I had the sender out of the tank I had the correct ohm readings at both ends of travel. In the tank I also would only see 3/4 full and the ohm reading was off with it full of gas. I verfied this on a buddy's scrap gas tank that had the top removed. My full tank reading was correct when the float was above the tank top by an inch or so. I put in a couple of "S" bends in the arm to shorten it up and still needed to make some small corrections but everything reads correct now. If you get creative with a long piece of stiff wire you can have someone watch the guage while you manually move the float to the top of the tank. It was pretty easy with the opening at the rear of the tank. I can't remember if your car has it in the back like my Road Runner or fuel comes in the top like a Charger. Good Luck Jim

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: dobie] #1469705 07/19/13 11:50 AM 07/19/13 11:50 AM
Joined: Dec 2009 Posts: 1,023 pa. D dan9 super stock
dan9 super stock D Joined: Dec 2009 Posts: 1,023 pa.	I needed one for a 70 Challenger. I called Kasing Dodge in Ellwood City Pa. They have the old parts books and are willing to look for a factory replacement. I got one in a Mopar box. I have not installed it yet but it does look of better quality than the repro that i have. If you call ask for Dan or Mike in parts.

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: dan9] #1469706 07/19/13 12:58 PM 07/19/13 12:58 PM
Joined: Mar 2003 Posts: 5,193 NEW JERSEY AARCONV master
AARCONV master Joined: Mar 2003 Posts: 5,193 NEW JERSEY	from reading what you have written..the clue was drops fast when you hit the 1/2 way mark...bent arm float wont drop fast...just a steady wrong reading i would say..seems like a bad rheostat on the float or a bad contact on that item

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: AnRT4Me] #1469707 07/19/13 01:14 PM 07/19/13 01:14 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	One thing that can be done is an electronic 'fix'. If you're willing and able. First you isolate the gauge circuit from the instrument panel voltage regulator--this is the crude device that alternately turn the voltage for the instruments on and off so that the "AVERAGE" voltage fed to the gauges is approx 5V. Crude is putting it nicely. You then build your own regulator with and SCR (silicon controlled recifier) and a few resistors--you can get the schematic on the internet. Part are cheap. The really cool thing, is that you can use a variable SCR in the circuit that is adjustable. Hey! Right on! You can now calibrate your gauge lower or higher. But keep in mind--this adjustment will change the entire sweep of the gauge, so if it always reads high or low no matter if there is a little or a lot in the tank it will work. It will not fix a situation where its already accurate at some levels but not at others.

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: AnRT4Me] #1469708 07/19/13 01:25 PM 07/19/13 01:25 PM
Joined: Mar 2003 Posts: 4,848 Memphis HemiRick master
HemiRick master Joined: Mar 2003 Posts: 4,848 Memphis	The sending unit should have 15 ohms resistance when full and 85 ohms when empty. Take care, Rick 68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Pacnorthcuda] #1469709 07/19/13 01:36 PM 07/19/13 01:36 PM
Joined: Jan 2003 Posts: 5,891 Athens, Greece Pyper70 master
Pyper70 master Joined: Jan 2003 Posts: 5,891 Athens, Greece	I went through this one year ago...I bought the 3/8" after market sending unit. Reads fine OUT of the tank...but IN the tank the most the gauge shows is 1/2 full. I bent it every which way. I finally gave up. I bought the marine float adjustment from AutoMeter. Bought the matching fuel level gauge...Even though my gauge cluster was repaired perfectly (and I mean perfectly to the extent of paying close to a grand to restore). I have a functioning fuel gauge again as I retrofitted the faulty Chinese sending unit with the Autometer version. Works great now...I hid my extra gauge in the glove box as it's something you rarely look at Family owned 1969 Charger R/T DualQuad 440/727/GVO/3.55s

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Pyper70] #1469710 08/01/13 11:21 AM 08/01/13 11:21 AM
Joined: Apr 2009 Posts: 43 Michigan A AnRT4Me OP member
AnRT4Me OP member A Joined: Apr 2009 Posts: 43 Michigan	THANKS A MILLION FOR ALL OF THE SUGGESSTIONS AND RECOMMENDATIONS TO EVERYONE!!!!! I WILL DEFINITELY BE TRYING SOME OF THEM!!!!!

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Pacnorthcuda] #1469711 08/01/13 10:07 PM 08/01/13 10:07 PM
Joined: Jan 2003 Posts: 5,439 So Cal Sinitro master
Sinitro master Joined: Jan 2003 Posts: 5,439 So Cal	Quote: One thing that can be done is an electronic 'fix'. If you're willing and able. First you isolate the gauge circuit from the instrument panel voltage regulator--this is the crude device that alternately turn the voltage for the instruments on and off so that the "AVERAGE" voltage fed to the gauges is approx 5V. Crude is putting it nicely. You then build your own regulator with and SCR (silicon controlled recifier) and a few resistors--you can get the schematic on the internet. Part are cheap. The really cool thing, is that you can use a variable SCR in the circuit that is adjustable. Hey! Right on! You can now calibrate your gauge lower or higher. But keep in mind--this adjustment will change the entire sweep of the gauge, so if it always reads high or low no matter if there is a little or a lot in the tank it will work. It will not fix a situation where its already accurate at some levels but not at others. Now what happens to the calibration of the water temp and oil pressure guages... Just my $0.02...

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Sinitro] #1469712 08/01/13 10:32 PM 08/01/13 10:32 PM
Joined: Jul 2007 Posts: 1,526 North Carolina cjskotni pro stock
cjskotni pro stock Joined: Jul 2007 Posts: 1,526 North Carolina	I bought the $60 sender from Van's Auto last year off of Ebay and it was spot on in and out of the tank. Proper reading for my car, I have been, told is 8-78 ohms and I measured 10-75 ohms on the bench. I mocked it up in the new tank I had and the arm was fine...no tweaking really to be done as far as bending it. Before this I had bought a cheap (then) repo for around 120$ around 2005 and it was off by a mile. It had a totally different resistance scale that went into the 100s of ohms. Granted this is a 1973 Charger but my gauge is pretty darn spot on now throughout the range down to 1/4 tank which is as low as I have gotten it before I get nervous and fill up. I have repro harnesses (stock) and re-done gauges through Instrument Specialties. I only have the little ground strap on the lines just like the factory. I guess I am one of the lucky ones?

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Sinitro] #1469713 08/01/13 10:53 PM 08/01/13 10:53 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Quote: Quote: One thing that can be done is an electronic 'fix'. If you're willing and able. First you isolate the gauge circuit from the instrument panel voltage regulator--this is the crude device that alternately turn the voltage for the instruments on and off so that the "AVERAGE" voltage fed to the gauges is approx 5V. Crude is putting it nicely. You then build your own regulator with and SCR (silicon controlled recifier) and a few resistors--you can get the schematic on the internet. Part are cheap. The really cool thing, is that you can use a variable SCR in the circuit that is adjustable. Hey! Right on! You can now calibrate your gauge lower or higher. But keep in mind--this adjustment will change the entire sweep of the gauge, so if it always reads high or low no matter if there is a little or a lot in the tank it will work. It will not fix a situation where its already accurate at some levels but not at others. Now what happens to the calibration of the water temp and oil pressure guages... Just my $0.02... l Re-read the part about isolating the gauge circuit. Do you think maybe that means isolating the circuit? I think it does. Yes my car has two instrument panel regulators, no reason you can't do that. You could put a separate one on EACH gauge if you want. It's cool stuff.

Re: GAS TANK SENDING UNIT ADJUSTMENT [Re: Pacnorthcuda] #1469714 08/02/13 11:05 PM 08/02/13 11:05 PM
Joined: Jan 2003 Posts: 5,439 So Cal Sinitro master
Sinitro master Joined: Jan 2003 Posts: 5,439 So Cal	Quote: Quote: Quote: One thing that can be done is an electronic 'fix'. If you're willing and able. First you isolate the gauge circuit from the instrument panel voltage regulator--this is the crude device that alternately turn the voltage for the instruments on and off so that the "AVERAGE" voltage fed to the gauges is approx 5V. Crude is putting it nicely. You then build your own regulator with and SCR (silicon controlled recifier) and a few resistors--you can get the schematic on the internet. Part are cheap. The really cool thing, is that you can use a variable SCR in the circuit that is adjustable. Hey! Right on! You can now calibrate your gauge lower or higher. But keep in mind--this adjustment will change the entire sweep of the gauge, so if it always reads high or low no matter if there is a little or a lot in the tank it will work. It will not fix a situation where its already accurate at some levels but not at others. Now what happens to the calibration of the water temp and oil pressure guages... Just my $0.02... l Re-read the part about isolating the gauge circuit. Do you think maybe that means isolating the circuit? I think it does. Yes my car has two instrument panel regulators, no reason you can't do that. You could put a separate one on EACH gauge if you want. It's cool stuff. Isolating the voltage limiter to one guage means that you have to cut up the PCB traces for that respective guage... Why not fix the sender issue correctly, toss that Chinese junker, get a good one and calibrate it.. Just my $0.02...

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