Fuel Gauge not working

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gary68plyfury

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Working the fuel tank the other day and my wrench hit the fuel gauge wire coming out of the front of the tank. Didn't think much of it until I noticed the gas gauge wasn't work.
Before I start taking stuff apart, what should I look for? The wire is still in the tank and gas isn't leaking Thankfully and I can turn it...Hopefully it should be able to turn/spin around.
Since it's only one wire for the gauge, does the tank need to be grounded?
Does the gauge work by resistance? I have no idea how the gauge even works. I didn't find any connections, in the line, that I could disconnect to measure for volts or resistance.

Thanks in advance.
Gary
 
gary68plyfury said:
Working the fuel tank the other day and my wrench hit the fuel gauge wire coming out of the front of the tank. Didn't think much of it until I noticed the gas gauge wasn't work.
Before I start taking stuff apart, what should I look for? The wire is still in the tank and gas isn't leaking Thankfully and I can turn it...Hopefully it should be able to turn/spin around.
Since it's only one wire for the gauge, does the tank need to be grounded?
Does the gauge work by resistance? I have no idea how the gauge even works. I didn't find any connections, in the line, that I could disconnect to measure for volts or resistance.

Thanks in advance.
Gary
Click to expand...

Is the grounding strap still there? This is a metal clip that clips on the metal fuel line and the sender. You may have knocked that off.

1688994634957.png


If the strap is there, unhook the wire and ground it. Your fuel gauge should read full when you do that. If it doesn't work, you must have done something to the wire.

The sender does work on resistance to ground.
 
Big_John said:
Is the grounding strap still there? This is a metal clip that clips on the metal fuel line and the sender. You may have knocked that off.

View attachment 605777

If the strap is there, unhook the wire and ground it. Your fuel gauge should read full when you do that. If it doesn't work, you must have done something to the wire.

The sender does work on resistance to ground.
Click to expand...
Thanks. I have no idea if the ground strap is there, but I'll look tonight.
So, if I ground the "Fuel Supply Tube" my gauge will read Full or it will read how much gas I have in the tank?
 
If your ground strap is missing, you can run a wire and clamp it at both ends. If you ground the wire to the sending unit, it will read full and not how much gas is in the tank. Do not hold it there too long, you don't want to damage the gauge.
 
57fury440 said:
If your ground strap is missing, you can run a wire and clamp it at both ends. If you ground the wire to the sending unit, it will read full and not how much gas is in the tank. Do not hold it there too long, you don't want to damage the gauge.
Click to expand...
Good things to know...... Thanks
I'm praying this works.
 
gary68plyfury said:
, if I ground the "Fuel Supply Tube" my gauge will read Full or it will read how much gas I have in the tank?
Click to expand...
If the strap is missing, and you ground the tube, it will read how much gas is in tank. The tube is normally grounded with that strap.

The way it works is there is a float attached to a rheostat. One end of the rheostat is connected to ground via the tube. The other end (or wire) of the rheostat connects to the fuel gauge. When the float goes up, the resistance lowers, when it goes down, the resistance increases. All your gauge does is measure the resistance.

1689002327346.png
 
Big_John said:
If the strap is missing, and you ground the tube, it will read how much gas is in tank. The tube is normally grounded with that strap.

The way it works is there is a float attached to a rheostat. One end of the rheostat is connected to ground via the tube. The other end (or wire) of the rheostat connects to the fuel gauge. When the float goes up, the resistance lowers, when it goes down, the resistance increases. All your gauge does is measure the resistance.

View attachment 605788
Click to expand...
Excellent.. Good to know if I have to test it. Thanks for the diagram and taking your time.
 
The Ground Strap is broken and looks like it's been broken for a while. I used a short wire to connect to broken sections but the gauge still didn't work. Then got more gas since I don't know exactly how much is in the tank, still nothing. I did try to sand the rust away on the ground strap but it didn't help. Tonight, I'll get a longer wire and ground the Fuel Supply Line to the body and see if that works.
 
57fury440 said:
It is possible the gauge is bad or is not getting power. Did you try grounding the wire to see if the gauge moved
Click to expand...
I didn't have much time last night. I try more tonight or soon.
When you say 'grounding the wire', where exactly should I try? I should run a wire from body ground to where exactly?

I was working on the gas tank and hit the Fuel Gauge Wire, so I'm guessing there's something broken at the gas tank but of course it could be elsewhere

Thanks again for taking your time to help.
 
If you ground the wire that is attached to the fuel sender on the tank the gauge should start to move towards full. Ground it to the chassis. Don't leave it grounded long as you can damage the gauge. If it doesn't move it may mean the gauge is bad, but it could also mean that the gauge has no power to it, or the wire has a break in it. If the gauge moves, then that is one thing that is not a problem.
 
Thanks to everyone for helping and taking your time.
I found that by putting a small piece of wire between the gas tank and the gas tank strap the dashboard gauge worked. So I'm having a grounding issue. I did put a wire to connect the broken Fuel Gauge Ground Strap but I'm guessing between the rust and the undercoating, I couldn't get a good ground, even after sanding it.
I did ground out the Fuel Gauge Wire and the gauge did start to move to the FULL but I disconnected it quickly.
One day soon, I'll work on a better solution.

Thanks,
Gary
 
gary68plyfury said:
Thanks to everyone for helping and taking your time.
I found that by putting a small piece of wire between the gas tank and the gas tank strap the dashboard gauge worked. So I'm having a grounding issue. I did put a wire to connect the broken Fuel Gauge Ground Strap but I'm guessing between the rust and the undercoating, I couldn't get a good ground, even after sanding it.
I did ground out the Fuel Gauge Wire and the gauge did start to move to the FULL but I disconnected it quickly.
One day soon, I'll work on a better solution.

Thanks,
Gary
Click to expand...
I soldered a spade connector to the face of the sender. Then just a wire to the body. Of course, you don't want to do that while the sender is in the tank....

DBiTpcR.jpg
 
I didn't do anything as fancy as Big_John, I just used a piece of wire and 2 small hose clamps. I'm glad it worked out. It is no fun driving around without a fuel gauge.
 
gary68plyfury said:
I'll use Map-Gas to do it quickly while on the car/tank... Yup, I'm joking.
Click to expand...
You know... I never used to figure that someone would solder that on the tank and I would never think to say anything because it's common sense... Right?

Lately, I wonder if common sense is optional.

l8CWs8o.jpg
 
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