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Filled the tank this morning on the way to work. 10 gallons total in the tank (half full):



Full tank. That can't be good.



Good back down to normal when the car is turned off.



Without my multimeter I can't check the resistance properly. But my guess is this sender is out of spec for the car. I may just have to get a new one.

If the resistance checks out and you want to try and fine tune the arm on that sender there are a couple of possibilities.

First would be to get a piece of straight stainless music wire the same diameter as the arm and a couple of electrical inline butt connectors to fit the wire. Connectors can be found at most parts stores if you don't have any and the wire at Amazon and some local hardware or hobby stores. Cut a length off the stainless wire as needed to extend the arm. Some space will added by the connectors since the wire will not go thru the stop in the middle of the connector. Cut the new length a bit shorter than what is needed to take the connector additions into account. Use the connectors and tightly crimp the new piece of wire into place. If the connectors are the insulated type I would take the plastic covering off but better would be to get bare non insulated connectors.

Another option would be to replace the arm and float entirely using a new plastic float such as this one.

Bend the wire in a 90 to support the new float and cut the other side of the wire to the length needed. With the old arm cut off somewhere just making sure the overall new arm will be the proper length, use the same crimp method to attach the new arm.

The needle going all the way to full suggests to me that you may have a short in the sender wire. I would check this first as it is a lot easier than dropping the tank.

Howard - I'll just have to order a new multimeter. No idea where mine went....probably lent it out to someone and it's lost to the wind. Good idea on cutting the wire and using connectors. I may need to try that.

John - No short in the sender wire. The needle on the gauge moves in accordance to how much fuel is in the tank, it doesn't just pin itself immediately to Full. This latest series of pictures was a test to see how the sender worked after I bent the float arm. It appears the ohms range on the sender is greater than what the gauge is designed for. I'll have to test it with a multimeter. I won't have to drop the tank again (thank goodness) because I finally cut a hole in my trunk floor. Should've done that years ago.

New multimeter from Amazon, so definitely not great quality. Apparently ohms settings only goes down to 200 at the lowest. The multimeter doesn't register resistance on the sender until the arm is all the way up in the full position. Without a good multimeter I really don't know what the sender is measuring. I'll have to borrow one from my neighbor.

In other news I had a weird battery situation the other day. Went to start it and nothing. All the bulbs in the car were very dim. Checked the battery and it was full charge, pulled it to have it tested and it tested fine under load. My negative cable is brand new 00 gauge, so that left the positive ground strap as being the problem. I swapped it out for a new one from Napa and the problem was solved. Car starts better than it ever has now.

The ground strap I bought was 2 gauge. The largest ground strap I'm seeing is 1 gauge. I wonder how much of a difference it would make if I replaced it with another modern cable of 00 gauge or if that is even necessary.

-Kevin

2 gage was original equipment. Your 00 cable must have a terminal illness. That is why the original 2 gage cables are often judged inadequate--the terminations are internally failing here at 70 years old.

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Thanks Ross. If a 2 gauge strap was original equipment then I'll leave that as is. To clarify, the ground strap on there before was also 2 gauge and was not original to the car, but definitely has been having issues with a good connection at the terminal, despite several cleanings to improve it. The 00 gauge wire is the one from the negative post to the starter and is brand new. I've not had any issues with that one at all.