My fuel gauge in my 66 mustang is broken and was wondering what the best way to troubleshoot the problem is. All of the other gauges work, the fuel one is just always on empty. It has been that way since I purchased the car I just haven't had the time to find out what was wrong. I really don't know much about gauges so I am afraid to do anything to them really. This might not matter and be an unrelated problem but last time I went to the pump and tried filling up it would only let about 2 gallons in and then stop. I kept shoving the nozzle back in until eventually it started overflowing and I had to stop. But slowly the fuel that was backed up drained into the tank. Any suggestions?
fuel gauge
- Thread starter rainman39393
- Start date
dennis112
15 Year Member
For the fuel gauge. Crawl under the gas tank and remove the sending unit wire plug that is at the front of the tank where the fuel line come from. Twist it back and forth a few times then do it while pulling.
Once the plug is off, ground the wire to the chassis. Make sure you have a good connection. Then turn the key on and see if your gauge moves toward full. If it does, the sending unit in the tank is bad.
If you still have no needle movement, you will need to remove the dash gauge cluster to test the fuel gauge. One side should have power (maybe 5-12 volts--test with a voltmeter with the key on) and the other side goes to the fuel tank. If you can determine which one goes to the tank, you can short that connector and see if the gauge needle goes to full. That tests the wire from the tank. Remember that you will need to turn the key on and since you will be making things live under the dash you need to be careful not to short things out.
If you have no voltage at the gauge, then the CVR found on the back of the cluster is bad--relatedly if it is bad your temp and oil gauge should also not work.
As far as filling the tank, there really isn't any correlation with the fuel gauge. My guess is that your problem is the particular gas station pump that you used. Modern gas pumps try to pump an incredible amount of fuel at a time to try to lessen your time at the tank. Older fuel systems cannot always handle it and gas will come flying back at you.
Once the plug is off, ground the wire to the chassis. Make sure you have a good connection. Then turn the key on and see if your gauge moves toward full. If it does, the sending unit in the tank is bad.
If you still have no needle movement, you will need to remove the dash gauge cluster to test the fuel gauge. One side should have power (maybe 5-12 volts--test with a voltmeter with the key on) and the other side goes to the fuel tank. If you can determine which one goes to the tank, you can short that connector and see if the gauge needle goes to full. That tests the wire from the tank. Remember that you will need to turn the key on and since you will be making things live under the dash you need to be careful not to short things out.
If you have no voltage at the gauge, then the CVR found on the back of the cluster is bad--relatedly if it is bad your temp and oil gauge should also not work.
As far as filling the tank, there really isn't any correlation with the fuel gauge. My guess is that your problem is the particular gas station pump that you used. Modern gas pumps try to pump an incredible amount of fuel at a time to try to lessen your time at the tank. Older fuel systems cannot always handle it and gas will come flying back at you.
