Fuel Gauge Sending Units compared

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I bought a decade resistance box. Somewhere between 60 and 80 dollars, I forget. Watching a gauge respond perfectly to 1 ohm increments and factory specs doesn't help the aftermarket sender problem.
agreed... just wanted to see if the gauge had a curve or was linear
 
If you use resistors to do some testing, make sure they are high enough wattage. At full scale, 12 volts divided by 13 + 10 ohms (gauge + sender) is about 0.5 amps. For the resistor, 0.5 amps times 10 ohms is 5 watts. A little quarter watt resistor will burn your fingers & change value after a bit. No need to ask how I know that.
 
make sure they are high enough wattage
I overkilled my resisters at 100W power resistors.

UH UH UH!
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Reality... gauges run at ~6V but your point is well taken
 
I overkilled my resisters at 100W power resistors.

UH UH UH!
View attachment 1715463367

Reality... gauges run at ~6V but your point is well taken

Well, I suppose it is a matter of interpretation, with the original regulator, it was a pulsed 12v, so 12 for awhile then 0 for awhile, so it averages to about 6. Math is still good, but only while it is at 12v. So on the average, you would be correct.
 
Agreed... pulsed DC we are both right ~50% of the time!:lol:
 

I just bought a new sending unit. I had to do a major rebend the fuel line so I could get it to fit into the tank. Which led to the end of it sitting higher in the tank that I am comfortable with. I left it as I think I was coming close to crimping the tube. Both the gasket and locking ring were way too small and had to reuse the parts I had just removed. I complained to the seller and he gave me a full refund, just this afternoon.

This is the 4th or 5th sending unit I have tried. They have all been abortions. But the strangest thing happened with this new sender. Before I went to the station to fill the tank, the gauge was on empty, When I finished filling the tank, that gauge was pinned to the full stop.
That is the first time, in over six years, there was a positive sign that the sender may be working properly. Keeping my fingers crossed
 
Keep a gallon in the trunk.
My old Spectra would read full for 3/4 of the tank. Then it would read 1/2 then 1/4 in about 50 miles then show empty. And you best be near a gas station
 
Keep a gallon in the trunk.
My old Spectra would read full for 3/4 of the tank. Then it would read 1/2 then 1/4 in about 50 miles then show empty. And you best be near a gas station
I have always kept 2 to 3 gallons of gas in a can in the trunk. I probably always will
 
On a related subject.
Sometime soon i'll be doing a custom gauge panel with Autometer Ultra Lite gauges.
Let say the stock sending unit is 80 - 10 like the original poster said.
Several different autometer gauges are available with differing ohm ranges. The ones that are closest to 80 - 10 are.
73 - 10
and
90 - 0
Which one of these should I order ? or which would get me closest to a properly functioning fuel gauge ?
 
Keep a gallon in the trunk.
My old Spectra would read full for 3/4 of the tank. Then it would read 1/2 then 1/4 in about 50 miles then show empty. And you best be near a gas station
I have a spectra in mine. I noticed the same thing as you did. With a full tank you think you're getting great gas mileage. lol. Once it reads 1/4 tank I go and fill up because it's like playing Russian roulette.

Great thread!
 
When my new spectra unit reads 1/8 of a tank it takes about 10 gallons to fill the tank. I like it that way - better to have lots of gas in the tank when the gauge reads low than the opposite!
 
My son has bought 3-4 of them, 2 were dodge trucks and 1 was a c body. All read empty when they are 1/2 full. So for a 1/2 tank it's a guessing game. Pure JUNK
 
Thread Necro!

I've been watching the new fuel sender / tank in my 1973 Duster since I installed it, and it would be easy to just keep track of miles to empty, but I like to have an accurate fuel gauge.

When I put the new fuel tank (Made in Taiwan) in, I got this sender from Year One: https://www.yearone.com/Product/chrysler-a-body/bg914

And after watching the OEM fuel gauge habits for many tanks, I see what I'm dealing with. It will go from reading Full to Empty in roughly 125 miles. My Slant 6 is getting right around 15 mpg. I will fill it up and write down the mileage, knowing I am good for 200 miles. I once drove it until it ran empty on a highway, and I got about 235 miles total that tank. I've looked at the resistance charts in this topic, and it seems about right.

I'm this close to getting an AutoMeter fuel gauge and their Fuel Bridge to calibrate it. I'll run a new wire from the tank to the fuel bridge to minimize resistance. I'll use their https://www.autometer.com/2-1-16-fuel-level-73-10-linear-z-series.html fuel gauge with it.
This wouldn't be hard to do, and I have it all figured out, but of course auto meter makes their calibration system wrong.

With my 1973 Duster on level ground, I'd use a protractor, string, and weight to get the angle of the tank as it is installed in the car. Then remove the tank, dump out any gas, and prop it up so it is at the same exact angle on the ground. Then use gallon jugs of water to count how many it takes to fill, then drain it out. Put in a half a gallon to set my "empty" point, then fill a total of 4 gallons for 1/4, 8 for 1/2, 12 for 3/4, and 16 for full. Then whatever extra amount the tank can hold, just to see.

Now this would be easy if you calibrated the fuel bridge from empty to full. But it is the opposite. You start with the Full setting and work your way towards empty. So I'd have to fill exactly 16 gallons, set full, drain out exactly 4 gallons, set 3/4, etc, or dump the whole tank and refill 12 gallons for the 3/4 calibration.

It is a pain.
 
And after watching the OEM fuel gauge habits for many tanks, I see what I'm dealing with. It will go from reading Full to Empty in roughly 125 miles. My Slant 6 is getting right around 15 mpg. I will fill it up and write down the mileage, knowing I am good for 200 miles
My dad drove his now my dart for decades that way
 
I think the real question is "why can't the repoppers" make the damn thing like the OEM? But that would require actual work.
EXACTLY! You beat me to it. So do you buy a meter match for your specific application, or do you have to set it up yourself.
I guess I am lucky. About 15 years ago, I bought a new fuel tank and got a repop sending unit at the same time. It has worked fine.
 
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