Fuel Sending Unit or Gauge?

[robertmee]

Is it Always the FSU or can the stock analog gauge itself have some correctible issues. Here's the behavior:

Full Tank, the Gauge reads mostly correct, might actually be a few ticks above F. As the tank empties, the gauge moves more to the right past F until the needle disappears.

Based on 0 to 90 ohm operation of the FSU, I'm guessing that I'm reading high and higher ohms all the time and I plan to check it with my meter once I start emptying this tank. But before I go to the trouble of yanking the tank, is there any 'known' issues with the gauge end that I should address?

 

[groumoutis]

I don't know the answer to the question but I have the same problem and when I changed my fuel pump I tested the sending unit by moving the float to figure out the problem and the needle moved sluggish but would move with the movement of the float I don't know if it is the baffles making the fuel to move slowly in the tank.

 

[Hacksaw]

FSU's do go bad. A few years ago, Shell/Motiva had a batch of gasoline with too much sulfur in it, causing FSU's to fail on a number of different cars.

You got to love poor QC at oil companies, while raking in massive profits.

Now, you could try the old wham the gas tank with a rubber mallet, when it's about half full, and see if that loosens it up.

"Floating" grounds can also cause weird things, so clean the grounding wires up.