Fuel Gauge SNAFU

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Pawned

Pawned

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I have been fighting the fuel gauge since day one.
I have tried everything, I even put in the Meter Match and the problem still exists.
I had a few OEM fuel gauges and now I am using an after market gauge.

I pulled the tank and removed the latest existing sending unit. I just hooked the unit up to the sending unit (unit) to the electrical system and the gauge work perfectly.

What it comes down to it the sending unit and/or the fuel gauge will not work properly with the sending unit installed in the fuel tank.
I checked the float and that is air-tight. I am baffled.
I have a new sending unit being delivered today, but it does not make sense to put it in knowing it will not works properly.

I am wondering if I seal the rheostat, on the unit, airtight if it may work. But these were never air tight and there may be a possibility of sparking if it is airtight

Anyone have any ideas?
 
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The aftermarket senders are linear, so what that means is the travel of that float arm will make the gauge appear to be accurate ( 1/2 the travel is 1/2 the gauge ). The problem is in the shape of the OEM tank. If it was cylindrical or cubed with this sender mounted at middle, a linear sender would be a lot closer to accurate. For all practical purposes, the OEM tank might be considered funnel shaped. OK more like a upside down funnel. Anyway... some have managed to get these linear senders more accurate by bending the float arm.
 
TrailBeast said:
Tank/sender well grounded?
Click to expand...
I have the OEM ground and added two additional grounds of my own.
But grounding is the only logical reason it is screwy. Actually a couple weeks ago, it worked perfectly for one trip in the car and then nothing. It has to be the grounding. I will try to add some other grounds and see if that my do it.

Any other ideas, please keep them pouring in
 
RedFish said:
The aftermarket senders are linear, so what that means is the travel of that float arm will make the gauge appear to be accurate ( 1/2 the travel is 1/2 the gauge ). The problem is in the shape of the OEM tank. If it was cylindrical or cubed with this sender mounted at middle, a linear sender would be a lot closer to accurate. For all practical purposes, the OEM tank might be considered funnel shaped. OK more like a upside down funnel. Anyway... some have managed to get these linear senders more accurate by bending the float arm.
Click to expand...
The problem is not that it was not accurate, it is that it rarely works. I put a Meter Match on it (which I will remove, if the grounding does the trick) and that will adjust for the non linearity.
My only saving grace is I know the exact mileage that leaves less than a quart in the tank
 
don't know much about electricity (darn it) and having similar problems with new AutoMeter and sending unit in '66 Barracuda - my mechanic has been told by AutoMeter to send the gauge and sender to them for calibration. Since the sending unit was designed to work with a gauge running on a 5 volt circuit board, could this be the problem?
:steering:
 
Check the wire going to the tank and all the connections if you have not done it yet, put a ohm meter on it and make sure it is good, or better yet a load light.
 
What about the voltage limiter on the back of your dash? Is it the original or an aftermarket solid state one?
Does your temp gauge work properly?
 
kiss said:
What about the voltage limiter on the back of your dash? Is it the original or an aftermarket solid state one?
Does your temp gauge work properly?
Click to expand...
I have an after market dash. I went thru 3 or 4 different instrument cluster configuration. I have 3 clusters and mixed and matched them . I went to after market cause the factory cluster was a mess.
It has nothing to do with the voltage regulator. These meters run on 12vDC. I rewired the car and replaced every wire in the car. The wiring is good.
The more I think about it, I am confident that the grounding of the sender unit is the problem.
I now have 3 grounds to the gas tank and sender. 2 grounds to the sender and one to the tank body
 
I have to use liquid gasket to get the sending unit to seat properly, so It does not leak.
I just put the tank back on the car, I will only know when it works when I fill her, but she will be up in
the air for a few more days. I will put in a couple gallons from the can. That should give me some indication. (tomorrow)
 
EUREKA - I think I've got it
Fuel gauge works to specs. Removed the Meter Match as not needed,

You may touch me

As I was putting things back together, I was thinking about the grounding and thought that the grounding was not the answer. Was not sure what it was but it was not the grounding. I guess I was wrong. (First time in my life, I have ever been wrong about anything)
 
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DrCharles said:
Either one works in this context ;)

So were you saying that the grounding WAS the problem?
Click to expand...
That is what I was convinced. After reassembling the car the more I thought about it I was having doubts, due to the ohm and voltage measurements on MY Duster.
I was waiting for the RTV? to cure before I added any fuel, I had time to second guess myself. (Big mistake).

As I had finished, everything I decided to go ahead and put gas into her. I have two separate grounding cables connected directly to the outside of the sending unit and another grounding cable actually soldered onto the gas tank itself.
It works wonderfully. But, until I go thru a tank of gas, I will not know for sure. But the problem appears rectified.
Keep in mind that I am using an after-market 12vdc fuel gauge. The entire Instrument Cluster is after-market with 12Vdc gauges and tach.
I also fought with this, with the OEM cluster. I have 2 - 4 clusters and mixed and matched them to make one good unit.
As it sits now, If the OEM fuel gauge operates to specs and the gauge barely reads any fuel or is way off, I would be concentrating on the grounding of the fuel sending unit,
 
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