Gas gauge not accurate??

[kenlainpro_]

Long time no see peeps. I used to check this forum all the time when I first got my 07, and now I need y'alls help!

Yesterday I was driving on the highway and my 4Runner stopped letting me accelerate. Turns out I had run out of gas!!! Even though my gauge said I had a quarter tank left, and my range said I had around 74ish miles left.

I've tried to google this and I see a lot of posts talking about their gauge just not working, that isn't my issue. Mine moves. Filled up the truck yesterday after running out and it went all the way to full. So it works, but at some point it stops being accurate.

Anybody know what it could be? I've been told a couple things it could be.

 

[xtremewlr]

Sounds like the sending unit is failing in the tank.

 

[MikeinNH67]

Sounds like the sending unit is failing in the tank.

This most likely. ^^^

 

[blackjackck]

Similar issue

I've been having similar issue on and off for the past couple of years. The fuel gauge and the range would be lower than the actual fuel on the tank. I had many theories and still hope its not the failing sending unit. Currently the gauge is working as it should and as I feel / hope its coorelated to a water leak that I've recently solved.

FYI - my water leak was coming in from my roof rack bolt holes. I added silicone in the holes and re-installed the bolts.

TBH - Im just hoping that the problem was water getting in to the cabin and some found its way to the sending unit, causing it to short some how and give inaccurate readings. I'm sure someone will correct me and tell me I'm wrong, which is very likely. BUT I like my delusion as I don't want to deal with replacing my sending unit.

LOL as I re-read this I'm not really contributing a thing to this thread. lol sorry good luck.

 

[xtremewlr]

I've been having similar issue on and off for the past couple of years. The fuel gauge and the range would be lower than the actual fuel on the tank. I had many theories and still hope its not the failing sending unit. Currently the gauge is working as it should and as I feel / hope its coorelated to a water leak that I've recently solved.

FYI - my water leak was coming in from my roof rack bolt holes. I added silicone in the holes and re-installed the bolts.

TBH - Im just hoping that the problem was water getting in to the cabin and some found its way to the sending unit, causing it to short some how and give inaccurate readings. I'm sure someone will correct me and tell me I'm wrong, which is very likely. BUT I like my delusion as I don't want to deal with replacing my sending unit.

LOL as I re-read this I'm not really contributing a thing to this thread. lol sorry good luck.

Yes, sorry, that is an incorrect assumption.

The sending unit that we are referring to here is part of the fuel pump and is physically located inside the gas tank. So there is no possible way a leak from your roof could have affected the sending unit.

Your roof leak could have affected other wiring inside the cabin and under the dash, depending where the water was routing itself. If it was driver side, I guess there's a small potential that it was causing havoc with your gauge cluster somehow.

 

[zguy1]

I'm betting that it is the fuel sending unit. I just recently replaced mine.

My issue was inaccurate readings below 1/4 of a tank. Initially I think it was an issue near 1/8 of tank but the issue seem to get worse over time.

Yes, you can continue to drive it with a bad fuel sending unit but you will need to resort to filling up the tank and tracking the miles driven. I did that for a little over a year. My 4Runner gets very consistent fuel mileage so it was easy to do; however, this becomes a challenge when you let others use the vehicle. I was forced to do this method after running out of gas twice.

A few dealers quoted around ~$750 to do the job. I ended up doing it myself. Assuming you are okay working with rusty fasteners, the job is easy with one exception in my opinion. The big vent hose on top of the tank is a real pain in the a** to get off. That is the hardest part of the job from my perspective.

The parts needed for the repair can be had for around $100 - $150. You will need a new OEM fuel sending unit, retaining ring and a new gasket for retaining ring. Of course folks will debate to also replace the fuel pump "while you are in there." It's your call, but I chose not too.

Since you should be familiar with tracking miles driven, you should be able to leave 4-5 gallons safely in the tank without running out of fuel. It is not hard to lower the tank with 5 or less gallons still in it. Once you have the tank out, you can easily power the fuel pump in the tank to remove the remaining amount in it. Installation will be easier with minimal fuel left in the tank.

Once you have the tank out, go back and check the big vent hose above the tank to see if the o-rings have moved or have been damaged. You will need to make sure that the o-rings are in tact or you will end up with evap codes. Don't let this happen to you if you take on this job. You don't want to do the job twice or have to take it to the dealer later. If that happens, you will pay over half of what the job would have cost initially at the dealership on diagnosing and repairing the evap leak.

Btw, you can rent a tool to remove and install the retaining ring. I recommend renting one of those as opposed to trying to tighten the ring using one point of contact.

Related threads below.

Fuel tank and protector removal - Please step in...
Erratic fuel gauge - bad fuel sending unit?
OEMTOOLS Fuel Pump Replacement Kit

 

[Bluesky 07]

This post describes my experience with the FSU and has pics, p/ns, costs, & other useful information.