Erratic fuel gauge - bad fuel sending unit?
 

Hello everyone.

I noticed weird behavior with my fuel gauge over the past few months. Sometimes the gauge reads a certain level but will change after restarting the truck sometime later. I parked the car yesterday evening and the gauge was near empty but the low indicator never turned on. This morning I was driving to the gas station and the truck shut off within a block of getting there. I was pretty sure I ran out of gas; however, the gauge was still above empty and the low indicator light was still not on.

I called roadside assistance and got a gallon of gas. The truck immediately started.

Has anyone ever replaced the fuel sending unit on a 4th gen? I assume that is what the issue is. Thanks!

It's most likely the sending unit but it could be the gauge. If you have a FSM there is easy instructions how to troubleshoot both.

The FSM will also have how-to instructions.

Just replaced my Fuel Sending Unit due to very similar symptoms. YMMV of course but the shop that did the install said it’s almost never the gauge. I debated doing the work myself but ended up very happy I didn’t.

My post about this is pasted below:
==
Had my fuel sending unit replaced and did the fuel pump for good measure while the tank was out. The video at the end of this post by someone named Rick S. provides an impressively detailed analysis of the issue, the short version being that I recognized a number of the symptoms described have been going on with my truck for years. Recently it started reading 1/4 tank low all the time. I'm keeping this truck forever so I fixed it and wanted to provide some pics and info.

For reference, my 4R is an '07 V6 with ~228K miles.

Cost: Parts ~$283 | Labor $393 with 10% veteran discount makes the total ~$676. Yeah, a lot of money, but probably about a month's car payment on a new vehicle so there's that. Someone comfortable doing the job themselves could do it for about $250 worth of parts (fuel pump kit, fuel sending unit, and the housing with the filter media and even that's kind of optional).

Chokes me to pay the labor but after consideration of the job itself and other things going on, it was worth it.

Parts list. OEM items are from Cobb County Toyota's online store.
8332060440 $ 95.70 GAGE ASSEMBLY, FUEL SENDER
2330050120 $ 37.97 Fuel Filter << This is the housing w/filter media in it
7714435010 $ 33.59 Fuel Tank Lock Ring << Didn't necessarily need
7716904050 $ 6.34 Fuel Pump Tank Seal << Gasket
Denso fuel pump & mounting kit - ~$109 from Amazon

Here's a comparison of the fuel sending units and the problem is obvious - the "track" where the end of the float arm moves gets worn away over time.

Old:
https://i.imgur.com/2ERjr3ql.jpg

New:
http://i.imgur.com/5d2V9wul.jpg?1

Interestingly, the 4th Gen fuel filter has two components. There's the strainer, which I have to say looked pretty clean for the age and mileage.

Old:
https://i.imgur.com/jO7AkBhl.jpg

New:
https://i.imgur.com/VceB6xIl.jpg

Then the housing itself has filter media inside, visible through the hose connections in this pic of the new one. I unfortunately couldn't get a pic of the old one but it was nearly black.

https://i.imgur.com/x4WUs2Hl.jpg


Here's the video by Rick S. Worth watching if you're having these issues or just want a very thorough understanding of the fuel sending unit and how it works.

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pretty easy to replace, just make sure the tank is as empty as possible, gas full moving around makes it a PITA

Thanks for the information! I happened to stumble across that video on YouTube yesterday evening. I think I am going to try and tackle this myself. I just need to plan for it. I may just change the fuel sending unit only like the gentlemen did in the video.

I have few other maintenance items adding up too.
- Shaking steering wheel at around 60 mph which gets even more violent when braking on the highway sometimes. First time I ever had that issue and my front pads and rotors were changed 30k miles ago around February 2021.
- Drain and fill of the trans fluid. Its been about 60k since it was last done.
- Rear brakes are worn and need to be replaced.

I still can't complain about this truck. It has 291k and still runs great.

Thanks. It doesn't look that bad. I'm a bit leery of some of the connections to the tank that need to removed from underneath the truck. I don't want to break any more things lol.

Pics of the top of the plastic tank...

Dealing with a wonky fuel gauge can be quite a headache. I totally feel your frustration – I had a similar issue with my truck a while back. It's so weird when the gauge plays tricks on you, showing different levels every time you start the engine. Based on my experience, you might be onto something with the fuel sending unit. I had to replace mine, and it did the trick.But if you ever find yourself in a situation where your truck decides to call it quits on the road, I've got a tip for you. I can share some info on reliable towing services that I've used before – just a little extra preparedness never hurts.

Yes, it was the fuel sending unit. I replaced mine earlier this year.