07/27/2026
There has been a major issue with fuel sending units not reading correctly in 70-72 Chevelle fuel tanks recently. I decided to look into it a little more as I’ve encountered this with the last several I have done as well as talked to others that had similar issues. I ohm out all sending units before installation. The one I am removing from this tank was perfect between 0-92 ohms.
After measuring the tank depth, 7” and the depth the float reaches on the sending unit 5.5” in this case, there is a difference of 1.5” of air gap between the float and bottom of the tank. That means the needle on the gauge won’t begin to move until fuel reaches the float. That equates to approximately 5 gallons of fuel give or take. That happens to be just under the amount of fuel I drained out of this tank before dropping it in which the gauge was reading slightly above E.
Not only that, but the car will run out of fuel before the tank is empty since the pickup also does not reach the bottom of the tank.
So, how does this get resolved? I have little faith in any of the parts suppliers to correct his problem.