Gas gauge is headbanging

So my gas gauge is fairly accurate except that it occasionally likes to jam out to heavy metal. Has anyone ever encountered this? I tried doing a search, but I couldn't find this exact issue. See video below.

https://youtu.be/0EUTrTvrXCU?si=pSPmTof3qpSmsh53

 

Does it do it all the time, or only at a specific tank load mark, like when you get near 3/4 full, 1/4 full, all the way full, etc?

IIRC, all 1st gens have the level sensor physically on the pump, and the (OEM) ones I've seen use a float that slides across a contact surface. If you get pitting or a dead spot on that contact surface, when the float jumps to that specific spot, the gauge will get no resistance [because dead spot], and dump to E, then when it gets a resistance signal again on a clean spot, it'll jump to normal level.

The only solution, sadly, is to replace the pump with the appropriate DENSO brand pump. Not a fun job, but I've never owned a semi-modern EFI truck where that job was easy and/or didn't involve having to pull the bed or drop the tank. It's something you don't want to do more than once.

 

It does it pretty much across the board, but is more pronounced with a fuller tank. Thanks @shifty` I figured the fix would probably involve dropping the tank. Looks like I'll just live with it for now.

 

More info for consumption here: https://www.tundras.com/threads/fuel-gauge-acting-weird-where-should-i-start-looking.110955/

Some other debugging you can do: https://www.tundras.com/threads/ran-out-of-gas.105081/#post-2703325

For the life of me, I can't find a picture of the sender. I think the older 1GT had a float with a round sender integrated into the pump housing. The newer ones may have the slide system, which someone on here posted. I dunno if you can just buy the sender separate, but you may want to play with slapping the tank and observing what the gauge does.

 

The assembly looks something like this:


The sender unit itself (83320-34050) looks like this:

 

Thanks for the info guys. I'll give the tank a few smacks as suggested. Mostly I'm just surprised to have an electrical issue like this as this is the newest, lowest mileage Toyota I have owned. It did sit for about a year after it's front end collision so perhaps the sender unit didn't get along with the old gas.

 

Sitting for a year or two with a low tank of gas would do it.

I've seen people report filling up a tank and dumping in a couple bottles of Techron will clean and rejuvenate the contacts on the sender. But I’ve never tried it.

It’s also possible the previous owner swapped out the fuel pump for store brand due to “no start” situation. We see people coming on here all the time in those threads saying they did the typical parts-cannon, replaced the starter and fuel pump, basically the two most difficult larger parts to replace, proactively. With a parts store brand. That will die in a couple of years and leave them right back in the same boat again.

Anyway, it’s just a thought, you may try the Techron thing, on a full tank, so you know the pump and its sender are submerged. It’s 100% going to be the sender at fault. That’s exactly what you’ll see when a sender or its float is behaving stupidly. It’s a very simple 2-wire resistance based system. I can explain how to test what resistance is coming off the thing if you want to confirm though. (You’ll need a multimeter)