2nd Gen Fuel Gauge Inaccurate, Shows Full Then Drops Quickly

Try this?

How do I recalibrate the fuel gauge - 2007 Toyota Prius

 

Does the tank need to be full for this to be done correctly?

SM-G960U ?

 

There is no prerequisite for what level the fuel is in the tank. The procedure sets the zero (or centered) value of the inclination meter, so it makes sense that the fuel level is not a consideration.

Centered Value Setting of the Inclination Sensor.
Perform the procedures to correct the inclination of the meter and inclination sensors when installing / removing / replacing the meter or after replacing the inclination sensors or main base.

The setting prerequisites are:

1. Connect the connector and install the meter securely in the position shown in the illustration so that it is inclined at a 20 degree angle to the vehicle's vertical line A.
2. 
   
3. Park the vehicle on a level surface.

 

I know it's been a while but my 2008 is having the same problem with the fuel gauge. Did the inclination reset procedure fix yours? Thx!

 

Most likely cause is that you have a worn spot on the fuel level sensor inside the tank. I have had to replace 3 or 4 fuel tanks on customers' Gen2 for this problem.

You can confirm the fault by waiting until the gauge just reads empty (flashing pip). Then remove the rear seat base and fuel connection access plate. Use a digital multimeter to measure fuel sender resistance per the factory service manual.

The sender has a resistance range 4 ohms (at full) to 110 ohms (at empty). Usually it will go way above that when it's bad - anywhere fromm 200 ohms to several mega-ohms (open circuit).

If this is what's happening, then the only repair is to replace the sealed fuel tank assembly.

Posted via the PriusChat mobile app.

 

This is the connector at the tank.

Posted via the PriusChat mobile app.

 

Thank you for the response. You're probably right, the reset procedure didn't fix it but I can't see spending $1300 on a new gas tank so I'll just fill up every 350 miles or so.

 

Not a permanent fix, but I've noticed on mine that if I run the tank pretty low (315-345 miles), then fill it all the way (after pump stops, slowly add another 1/2 gallon), the gauge works much better for me over time.

It used to read empty at about 50 miles, now it gets up to 280 miles. Sometimes it will still act weird.