Weird Fuel Gauge issue

[20034RunnerV84x2]

So I noticed this on my way to Louisiana (from Atlanta) for the holidays to visit my sister. When I full up the tank, the gauge will go to full, but when it is done pumping and I'm leaving (the truck hasn't moved yet) it will go down, sometimes to 3/4 yet I haven't moved. This is an example from last night, filled it up (from a bit above empty) and before it even moved the gauge went down. I have no idea what the problem is, it can be overflowing and it will still go down. Any help is greatly appreciated. Hopefully is doesn't have anything to do with the EVAP system. (For some reason I can't attach the pics, but it took 19.3 gallons, was at full then went down to a bit over 3/4) TIA

 

[20034RunnerV84x2]

Bumpin it up

 

[20034RunnerV84x2]

No one? D:

 

[NJshadow93]

So I noticed this on my way to Louisiana (from Atlanta) for the holidays to visit my sister. When I full up the tank, the gauge will go to full, but when it is done pumping and I'm leaving (the truck hasn't moved yet) it will go down, sometimes to 3/4 yet I haven't moved. This is an example from last night, filled it up (from a bit above empty) and before it even moved the gauge went down. I have no idea what the problem is, it can be overflowing and it will still go down. Any help is greatly appreciated. Hopefully is doesn't have anything to do with the EVAP system. (For some reason I can't attach the pics, but it took 19.3 gallons, was at full then went down to a bit over 3/4) TIA

Does it stay at 3/4 until you actually burn through a quarter tank of gas or does it run down like normal as if you only filled up to 3/4 tank?

 

[20034RunnerV84x2]

Stays there. It's getting worse. I put more in earlier & now it's dropping to a half. It'll go up tiny bits but never shows the correct reading unless it's around half or less. Then it goes down normally. I honestly hope it isn't the sending unit.

 

[rallymarty]

I am currently struggling with this issue as well. Our '03 has +200k for mileage, so I'm expecting this to be the sending unit as well.

Ours was doing same thing, could only get it to register full tank if I filled all the way up to top of neck. Was consistently stopping at 3/4 tank, and now wife said it's been acting goofy and jumping around.

Will monitor this thread, if I get a solution, I'll post it.

 

[20034RunnerV84x2]

Mine only has 98k miles on it though. I know there was a TSB for 99 model years (a whole different generation) and there was some kind of ordeal with shell and their sulfur levels that would screw with the sending unit and make it go bad. It isn't going over 1/2 a tank now. I'm pretty sure Toyota has two separate sending units for the gauge itself and the low fuel level light, but I'm not sure. Just aggravates me that something so important goes out on something that isn't that old. Thanks, Toyota.