Re: 69 b body sending unit fuel in tank question
[Re: mikemee1331]
#1789003
03/27/15 01:30 AM
03/27/15 01:30 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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Lincoln Nebraska
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Michael, I'd do some more cruisin
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Re: 69 b body sending unit fuel in tank question
[Re: MidPenMopar]
#1789004
03/27/15 09:33 AM
03/27/15 09:33 AM
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Joined: Apr 2010
Posts: 4,154 bethlehem pa
mikemee1331
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Quote:
If you are replacing the sending unit let me know if you ever get one that reads correctly. I have gotten two so far that read 1/4 tank off. No matter what i do to try to fix it i cant.
yep that's what I've done and nope, it's a 1/4 off. it's one of the newer, new repro's. I won't get into the ohms and all but it appears the float position is off versus the working original. won't know until I pull it back out and hook up a meter outside of the tank.
Robert, then I won't know how much fuel is in the tank. right now I know it's 10 gallons which is a little over half full. new sender only shows under a 1/4. I have an electric pump so it's not a huge issue except i'm running out of vacation time
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789006
03/27/15 10:33 AM
03/27/15 10:33 AM
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mikemee1331
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Quote:
Slide the filler tube out and peer inside with a flashlight. You'll see exactly where the fuel level is in relation to the sender. You can reach the float and raise it with a broomstick to measure ohms at different float levels while this sender is still installed.
ah! we think alike! no dice on pulling the tube out without turning it into a major job. i'll just pump out half of what I put in. i'm re-plumbing anyway
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789008
03/27/15 12:33 PM
03/27/15 12:33 PM
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Joined: Dec 2003
Posts: 36,840 South San Francisco, Californi...
MidPenMopar
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Quote:
Has anyone tried readjustment of the gas gauge to tune it to these repop senders? I have a box of 68-70 B Rally gauges and they have small adjustment holes in the back to move the pointer.
All i have tried is trying to change the position of the float arm. I had it cut down a little and that helped some but not much...I had no idea about the gauge adjustment though?
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789010
03/27/15 02:20 PM
03/27/15 02:20 PM
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mikemee1331
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Quote:
Has anyone tried readjustment of the gas gauge to tune it to these repop senders? I have a box of 68-70 B Rally gauges and they have small adjustment holes in the back to move the pointer.
interesting... I just drained, pulled, and ohmed both units to get float positions and ohms as close to each other as possible. put the new sender back in, refilled with the 10 gallons and I only gained 1/2 a quarter of a tank. I went from being under a 1/4 to just over. doing this out in the cold on your back is no picnic!
I don't have a ralley cluster but I do have a spare non ralley cluster and i'll look at what you suggested.
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789011
03/28/15 12:05 PM
03/28/15 12:05 PM
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Joined: Jun 2012
Posts: 1,386 Philadelphia PA
Pynzo
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This gauge has seen better days- the thermal wire has burned due to a bad voltage limiter. The adjuster teeth are easily turned with a small blade and change the position of the pointer. I figure that a gauge can be fine tuned to the sender prior to installation by hooking up a circuit with a 3 volt power source and enough 18 gauge wire to match what is in the vehicle. Set the sender for empty and adjust pointer to far edge of E mark on gauge, raise sender arm to full stop and adjust pointer to far edge of F mark, recheck E setting, and you should be done. Unfortunately you'll need to remove the gauge from the cluster to do this. Edit- this pic is of an Oil or Temp guage- Gas guage internals are slightly different but work the same way.
Last edited by Pynzo; 03/28/15 12:50 PM.
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789014
03/28/15 01:32 PM
03/28/15 01:32 PM
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Quote:
I figure that a gauge can be fine tuned to the sender prior to installation by hooking up a circuit with a 3 volt power source
You need 5 volts. The gauges were calibrated in 3 different modes. E-1/2-F. There is a factory tool that allows you to do so. It is just a ground with resistance for each mode. I have that tester and I can measure each mode for anyone trying to tune your gauge. Then all you need is a resistor or resistors to equal that OHM for calibration. The factory manual should have a write up as I remember it instructing you how to do it. If you adjust it for just one mode as mentioned above it will or can affect the other gauge readings.
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789017
03/28/15 02:43 PM
03/28/15 02:43 PM
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mikemee1331
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Quote:
Looking at a '70 Charger/Coronet FSM, it lists a tester, C-3826 for the gauges, with low medium and high settings. The section on Fuel Tank Sending Units has a figure of 73 ohms empty,+or- 12 ohms. Full setting 9.6ohms +or-1 ohm. What are the values of the L,M, and H settings for the tester?
my original was 68 at E and 13 at full FWIW. E on the gauge was always below the line and full a little above.
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Re: 69 b body sending unit fuel in tank question
[Re: Pynzo]
#1789019
03/28/15 03:14 PM
03/28/15 03:14 PM
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mikemee1331
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I don't really suspect my gauge. it's read the same for 30 years with the old unit and prior to this car I had another (non-ralley) and it too read the same. i'm going to answer the rest of your question over in the other thread I started on the new unit to kinda corral the whole thing. a very un-moparts thing but...... https://board.moparts.org/ubbthreads/show...e=0#Post8406855
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