Team Chevelle banner

Weird fuel gauge reading issue

490 Views 13 Replies 7 Participants Last post by  LevonH
I never really had filled my gas tank to the neck before but a few weeks ago I did. As soon as I started it up at the gas station the needle went way past F. See pic below. I just figured it was an in accurate gauge. So I have about 100 miles on it since and it’s still reading past full. Could the needle be stuck?
I put a borescope in the tank. It’s about 1/2 full and the float is at that level, not stuck up high. Thoughts?
See less See more
1 - 7 of 14 Posts
Usually, that's a wiring issue, but a wiring issue as soon as you fill the tank?
Exactly my thought.
So I pulled the connector in the trunk. Grounded the tan wire coming from the sending unit that runs back to the the dash. Turned the key on and the gauge reads E.
I then put 90 ohms resistance between that wire and ground and the gauge reads a tad past F. So the gauge and the wiring is good.
I then ohmed out the tan wire going to the sending unit and it reads 15meg-ohm. 🙁. Since this issue started immediately upon filling the tank, I think it’s safe to assume that the sending unit arm went to the full position and then something internal broke. That sucks.
  • Like
Reactions: 1
I siphoned it and yanked it. Not too bad. Took about 20 minutes. I pulled the sending unit. It’s bad.
See less See more
  • Like
  • Sad
Reactions: 5
That’s what I get for filling my tank all the way up.
  • Like
  • Haha
Reactions: 3
Jim, thanks for the follow up. Yea, I have the original AC Delco unit and it has the strap leading to the push through pin on the underside. I checked right on the strap itself of the float and it was open. After moving it back and forth a few times, I got a reading out of it but it was not correct. It read 25 ohms at the bottom and 135 ohms at the top. It was intermittent as well. Would occasionally go to the k-ohm scale and then open again. I thought about contact cleaner but since it’s inside the tank, I was not going to take a chance on it failing again a month later. I ordered a Dorman replacement. Should be here today. $33 on Amazon.
Here is the original;
See less See more
Levon, the wiper assy is mounted to the side of the fuel tube, so it just sits in the tank submerged.
I did open it up anyway. Pretty worn. I put the new one in today. All good now 👍
  • Like
Reactions: 2
1 - 7 of 14 Posts