Fuel Gauge Issues
 

1999 4Runner -
Fuel gauge issues -
After a battery change my fuel gauge which was working normally now shows either Full or Empty -
When I turn the key on and start the engine the gauge will show Full -
As soon as I start driving the gauge snaps to Empty -
There is no middle ground even if the tank is not completely full -
I disconnected the sender under the back seat - no change.
I did the reset procedure - no change.
It doesn't seem like it is the sending unit since the problem started instantly, not gradually.

Most of the posts or fixes I see related to fuel gauge issues have to do with a bad sending unit.

Any thought anyone?
This is really perplexing.

There is a TSB for the 1999 model year {MFG DATE:98/NOV+99}.. (should be a Recall) either your sending unit needs to be changed or the sending unit and the Computer board behind the dash needs to be changed as they are known defective parts thats rolled off the factory, the board in the dash has a built in inclinometer for accurate fuel level readings on hills ironically, check with dealer they will pre-order the parts. I had to do both, dealer quoted me under $800CAD taxes included all in so I went for it because they said if it didn't work they would pay to fix the issue, and there was no point in playing around with aftermarket stuff, and at the time the OEM parts where $400CAD taxes included, and dropping a 18 year old fuel tank sucks.