66 Coronet, how much gas for Needle to Move on Gauge?

[SassyPants]

First Shout out to Mr. Hall. This is the tool of the day from a previous post. . Thank you.

Put 2.5 gallons of gas in SP last night and used an above or like it to pump the fuel from the Tank up to the Carb. Worked like a Charm. Took about 1 minute of pumping to get the fuel through the system.

So, the gas gauge needle has not yet moved with 2.5 gallons in the tank. Need I put in more or start the dreaded work on the Sending Unit? If this is not enough to get the needle to move, about how much need go into the tank to get needle to move? If I have to take down the tank, don't want to put too much in. OH, New Tank, New Sending Unit, New Fuel Line, old gauge. Best, B.

 

[David Stillie]

From bone dry to 1/4 my Charger took 8 gallons. The first 4 gallons didn't move the needle.

 

[Bad B-rad]

Did you get a new ground strap, or reuse your old one?

 

[Bad B-rad]

Can try just running a ground wire for test, if you don't currently have one on your new tank and sending unit.

 

[SassyPants]

Great Question. Here are the pics of the Sending Unit. I will explain the deal afterwards.

 

[SassyPants]

OK, so if you look at Pic 1, you see the sending unit and just above that you see a Stainless Steel Screw that goes into the Shock Mount Brace. In Pic 2, that black ground line goes to the corner of the Fuel tank and you can see another Screw that I drilled into the tank. Pic 3 is a diff view of the sending unit.

I wonder if perhaps I did not get a "good" ground to the Shock Towers, or do I need to Ground directly to the Sending unit? Thanks again, B.

 

[SassyPants]

Here is what it looks like under the Ground Wire that I put on. Also drilled Fresh Hole for the screw to go in. Seems like it should ground?

 

[SassyPants]

Here is the end that is grounded into the Tank.

 

[SassyPants]

Can try just running a ground wire for test, if you don't currently have one on your new tank and sending unit.

Thank you, I think the Tank is pretty well "grounded" by the pics above? But B-Rad, if you have a suggestion on another way to test, I am all eyes/ears. Thanks in advance. B.

 

[SassyPants]

Otherwise, I will put more gas in and see if the needle moves. Fingers crossed. B.

 

[Beekeeper]

There is a reserve built into the tank and sending unit design when it’s on E there’s fuel left in the tank. First thing to do would be to verify the gauge works by grounding the sending unit wire directly to the chassis just long enough to see the gauge deflect make sure the ignition is on run. Next verify the sending unit is grounded to the chassis by using a multimeter set on ohms check between the chassis and the sending unit nipple where the fuel line connects should be real close to zero. If all that checks out measure the resistance value at the sending unit with the multimeter on ohms between the chassis and the stud on the sending unit where the wire attaches. 73 ohms or so is empty 10 or so is full.

 

[SassyPants]

I will do. THANK YOU, THANK YOU. You guys are GREAT!! Best, B.

 

[Beekeeper]

I edited my post with info on the sending unit test as well

 

[diesel_lv]

I put 4 gallons in brand new tank w new sending unit. Showed empty. Figured I'd figure it out later. Filled up after it was running n showed a bit over 3/4 at full so I guage works, just not Extremely accurate. I keep a note pad n pen in glovebox and log miles n gallons at fill ups. Just started doing it and FI is in learning stage so do know my mpg or distance per tank yet.

 

[Bad B-rad]

I would think the ground you have should work, I think Beekeeper has a good point.
Also the multimeter test will also tell you about ground

 

[SassyPants]

Thanks again to all. Tomorrow, I will give things a check via multimeter. I appreciate all of the kind help. It means a lot to me, especially when it comes to Elec stuff. I do well with most other stuff, but for some reason that Elec stuff just has me, sometimes. There must be someone who I can blame for that, isn't there?? . Now, back to Happy Hour. . Best, B.

 

[SassyPants]

There is a reserve built into the tank and sending unit design when it’s on E there’s fuel left in the tank. First thing to do would be to verify the gauge works by grounding the sending unit wire directly to the chassis just long enough to see the gauge deflect make sure the ignition is on run. Next verify the sending unit is grounded to the chassis by using a multimeter set on ohms check between the chassis and the sending unit nipple where the fuel line connects should be real close to zero. If all that checks out measure the resistance value at the sending unit with the multimeter on ohms between the chassis and the stud on the sending unit where the wire attaches. 73 ohms or so is empty 10 or so is full.

Bee, thank you. So, after a bit of a bike ride this morning, my wife and I did the tests above.

1. Battery hooked up, key on, from a good ground to the Sending Unit Wire and Bam, it started on its way up. So, Check on the first item.

2. Multimeter on ohms, known ground, to the nipple on the Sending Unit Nipple, Zero on the Multimeter. Check.

3. Multimeter on Ohms, from Know ground, Stud on Sending unit, first read was 80. Recheck it was 70. Recheck it was between 70 and 80 if we gave it a bit of time to settle in.

So we have more gas to put in the tank and will see if the Gauge moves, if not will check Ohms again as in number 3 above from stud to known ground, just in case.

I am setting my expectations appropriately, that a full tank will read half full on the gauge. Hoping for better.

Thank you all for your patience and help. Best to all, B.

 

[SassyPants]

Happy Hour Update (30 minutes early, butttttttt)-- Ms. M got 3 gallons more gas to pour in SP. That should put us at right about 5.5 gallons in a brand new tank. When we did the test Number 1 in previous post, the gas gauge went up to half. When we disconnected the battery and of course the ground to sending wire, it came only back to quarter tank on the gauge. It did not return to E.

So, when I turned on the switch after putting in the gas, the needle did not move. It stayed on Quarter tank.

So, unhooked the Sending Unit Wire and put multimeter on Ohms. From a good ground to the Stud on the Sending unit and it reads between 13 and 15, which seems high based on the reading above. What think? If it is 13 to 15 and 10 is full, one would think it ought to be more than quarter on the gauge. But, if one rather does the math, 5.5 gallons is about a quarter tank, me thinks? Is there a mystery to be solved here? Best B.

 

[Beekeeper]

Is this a new sending unit? From you description of the first test it sounds like a faulty gauge it should have returned to E

 

[SassyPants]

It is a New Sending Unit. When I did the Ground to the Sending Unit Line test, the gauge went to half. I quickly pulled the wire and it settled back to a quarter, but then "stuck" there. We turned off the key and it still stayed at quarter tank. Thanks Bee for you coaching. Any other questions I can answer or tests that I can do? Best, B.