Crazy Gas Gauge

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PistolGrip

PistolGrip

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I just finished assembling a '66 Barracuda. I put in a new gas tank, fuel filter & sending unit. When I filled the tank, the handle clicked off and the gauge read Full. I drove it about 40 miles & it read Empty. I put in 3 gallons & it read Full again, only to drop to Empty in 40 or so miles. I knew I had gas in it, so I drove it 50+ miles with the gauge on "E" - which is a bit unsettling. I put in a second new sending unit & it is doing the same thing. The gauge itself tests fine. I was wondering what the gizmo that looks like a Silver Salute with a black wick (pictured below) does. I believe it has something to do with the gauge & maybe that's the problem - or.....anyone?
Thanks,
Mark

Gas gauge part.jpg
 
Non OEM sending units at not worth the metal they are made from.

The
PistolGrip said:
Silver Salute with a black wick
Click to expand...
Is a capacitor to reduce noise on the radio and help the instrument voltage regulator last longer.

The typical sender will have a resistance range some are 10 to 80 ohms. Part of the problem is the float arm is way too short, the other is the aftermarket senders are not designed for the shape of the tank.

As Lord sparky pointed out there are a ton of posts about the issue.

Your best bet is if you have your original and it is not a rust bucket send it out to be rebuilt.

There are devices called meter match that can help.

This is a good post
Close as you will come to getting an OEM fuel sender..

Here is another

Fuel Gauge Sending Units compared
 
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The 66 has a voltage regulator INSIDE the gas gauge. It takes the 12 volts from the battery and reduces it to around 5 volts. My guess is Ma Mopar was still transitioning to a complete 12 volt system.

Anyhow, it's a crazy set up. The regulator looks t a set of points and opens and closes to reduce volts to run the gauge.

Oftentimes the regulator fails. The temperature gauge uses the same 5 volts so if the temperature gauge is working, the regulator is good.

Another thing that causes problems is not having a ground strap at the gas tank. It looks like this and provides a ground from the gas output tube on the sending unit to the fuel line.
s-l225.jpg


You can also just add your own ground from the sending unit to chassis ground.

I'll post up some links that may help you narrow it down.
 
Good luck!

I replaced my internal voltage regulator with a solid state regulator. It works but now my stinking sending unit is way off. I just reset my trip meter and track mileage. When my gauge hits E, I still have about 6 gallons.

IMG_20141106_190827.jpg
 
I too am tired of fighting these crap aftermarket sending units. Mine reads Full correctly but will drop to around 1/4 tank after using about 5 gallons. From there it quickly drops to empty then I have no idea whats in it.
So I bough some phenolic sheet to cut out some blanks to reproduce the resistor for the sending unit. The original ones liked to warp and the rivits would corrode and fall off. The wire needed is Nichrome resistance wire, 36awg (.0005"). The sender uses 46" of this wire and should ohm out around 85Ω.
Wrapping the coil is going to be hard to do. My first attempt did not turn out well.
 
There's a few ways to approach a workaround
1...Very FIRST thing is to mockup power, a suspected working IVR, the gauge/ cluster, and TEST RESISTORS

c-3826-jpg-jpg.jpg


and see if they give the readings expected, and then........
2...unubtanium OEM sender "from somewhere"
3...For later A's, don't know about early, someone posted that there's an egag seller selling VAN senders that seem to be better and can be made to fit the A bodys. These have the required tapered resistor
3....There is a couple of products that can electronically correct the sender. "Meter Match" is one of them...........TechnoVersions - MeterMatch for Analog Gauge Correction

4...Again I think for the late A's someone on here did a data sheet on resistance vs sender movement. You will have to search for it, bend the arm, adjust the float, etc.

For me, I'd figure a way to make it accurate at MT to start with that is really the important "end"
 
I just ordered a couple of the ebay sending units to give them a try. They look to be made exactly like the original so we will see.
64-70 Dodge A100 Truck/Van, 67-70 A108 Dodge Van Fuel Gas Sending Unit 5/16" | eBay

I do have a meter match for this car and have one installed in another car. I just dont want to pull the dash out because its fragile.

66fyssh, they dont need to design a new sending unit...just make an accurate copy of the original. The Chinese are good at copying stuff. Not sure why we cant get a decent sending unit for our mopars.
I wonder if the ford and chevy guys have the same issues?
 
PistolGrip said:
I just finished assembling a '66 Barracuda. I put in a new gas tank, fuel filter & sending unit. When I filled the tank, the handle clicked off and the gauge read Full. I drove it about 40 miles & it read Empty. I put in 3 gallons & it read Full again, only to drop to Empty in 40 or so miles. I knew I had gas in it, so I drove it 50+ miles with the gauge on "E" - which is a bit unsettling. I put in a second new sending unit & it is doing the same thing. The gauge itself tests fine. I was wondering what the gizmo that looks like a Silver Salute with a black wick (pictured below) does. I believe it has something to do with the gauge & maybe that's the problem - or.....anyone?
Thanks,
Mark

View attachment 1715547562
Click to expand...
Mark,
Please check out John Wolf and Co in Ohio...they rebuild all types of vintage gauges and Mopar OEM fuel sending units to factory specs. A number of FABO members have sent their units to him and were very happy with his work and now their fuel gauges are spot on. A lot of members try to rig up a Rube Goldberg system for their units and they never read correctly. Save yourself a bunch of aggravation and send it to him for rebuild. Let us know how it turns out.
Good Luck,
Greg
 
318MoparGuy said:
Mark,
Please check out John Wolf and Co in Ohio...they rebuild all types of vintage gauges and Mopar OEM fuel sending units to factory specs. A number of FABO members have sent their units to him and were very happy with his work and now their fuel gauges are spot on. A lot of members try to rig up a Rube Goldberg system for their units and they never read correctly. Save yourself a bunch of aggravation and send it to him for rebuild. Let us know how it turns out.
Good Luck,
Greg
Click to expand...
I'm going to take a breather for a while & regroup later. Unfortunately when I bought the car there was no gas tank/sending unit at all, so I bought both new thinking nothing could go wrong (what was I THINKING?). For now I'll keep track of how much gas I put in & synchronize that with my trip odometer and do the math @ 15 mpg (est) and ignore the gauge. If you see a Yellow '66 Barracuda with a black vinyl top stopped dead on the berm of I-75....at least wave as you go by. :)
 
I will let you know how I make out with this ebay one. It looks spot on in the picture.
 
I bought one of the A100 senders, another member posted a great wrightup on it, this weekend I'm going to give it a real-world test, one gallon at a time.

Will post the results.
 
Yeah let us know, im tired of smelling the gas can in the trunk of the old dart sport. I ordered two of the A100 sending units. If they work out im putting them in all three of my cars.
 
The one I got was exactly like the one in the post, even the float arm was twisted and the cage for the sweep and wire not exactly square.

It is a little different than OEM.
OEM pickup is s bit longer and has a slight bend down where the filter attached and the float arm is an inch shorter than OEM

But the resistance board is almost the same shape so we will see
 
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