I have a 67 vette, the fuel gauge reads at half full. I have replaced the sending unit in the tank. For about a month this worked, it went to 3/4 on the gauge, I replace the dash and engine wiring over the winter. Now it's back to 1/2. I would like to solve this problem soon. Thanks

If the signal from the sending unit is correct, the problem would be in the gauge on the dash.

if it worked for a short period of time after doing the pump/sending unit the check the connections going to the pump/sending unit they would have been moved around doing the pump

it might be the floater inside the gas tank or the sending unit which sends the info to the ecu and tells you how much gas you have replace that and it should work, sometimes it can be a faulty cluster gauge too

It sounds like the ground wire to the sending unit(located in tank) might be loose. The ground wire usually starts at the top of the tank at the sending unit and goes to a portion of the frame. Or the sending unit could be going bad.

It sounds like a problem with the fuel gauge sender unit in the fuel tank which has worn out and gone open circuit and needs replacing. Access to the unit is usually through a removable plate in the floor in the rear of the vehicle. Disconnect the wiring connector and any hoses and then remove the securing screws. Replacement is done by reversing procedure.

It sounds like the sending unit has a dead spot on it causing it to read inaccurately. The tank would have to be dropped and the sending unit replaced. Check out this page and illustration to better understand what's going on. "How a fuel gauge works"

Sorry to say,but the fuel sending unit is the problem,the fuel tank will have to be lowered out of the vehicle to replace the unit.If the fuel sending unit is not available by itself you will have to replace the whole fuel pump assembley.

You are probably looking at dropping the fuel tank down and removing the float and sending unit ( all in one unit). Once it's taken apart, you may see that you can fix it or you may have to replace it.

You have to drop the tank, on your fuel sending unit if the "float" that tells the gauge how full your tank it. These like to get holes, or jam up. So it is only going up half way, and your gauge only reads half full. So it could have a hole, it could be sticking, or a variety of things. Before you go doing all that, I'd check the ground wire off your unit, since it is working doesn't sound like a ground issue, but they can be tricky. Good luck.

This is a normal concern.
The instrument cluster uses 4 different operating modes to calculate the fuel level:
Anti-slosh (default mode)
Key OFF fueling
Key ON fueling
Recovery
After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.
The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from empty (E) to full (F).
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The key must be in the OFF position throughout the entire refueling of the vehicle.
At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms.
If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The transmission is in PARK (P).
The key is in the RUN position.
At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
In key ON fueling mode, a 30-second timer activates after the transmission is put into the PARK (P) position (automatic transmissions). When the 30-second time has elapsed and at least 15% of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of PARK (P), the fuel gauge strategy reverts to the anti-slosh mode. The key on refueling mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.
Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level input during a refueling event. Missing fuel level inputs result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
The instrument cluster is in the anti-slosh (default) mode.
The actual fuel level in the tank is greater than what is being displayed by the fuel gauge