So now that I have the major things done to my 4Runner that were needed, I feel it's time to start addressing this small thing that has been driving me NUTS for the past 6 months or so.

When I fill up my tank, for the first 100 miles if I hit any sort of bump, or accelerate quickly, my gauge INSTANTLY reads empty and the light flashes.

The only way to bring it back is to turn off the 4Runner, and re-start it. Even after doing that as soon as I accelerate onto the freeway or hit a pot hole, back to empty.


A bit of background: My fuel gauge has never been accurate. When I bought it back in 2010 I picked it up in Portland with a full tank. Drove to Seaside (~80 miles) and it read just above empty. From there it was the same thing everyone else reports with fluctuating fuel levels throughout the tank. It did not however, ever read full when it was empty. It always let me know when it was time to fuel up.



SO my question is... Should I just replace the sender in the tank...? Or is there something else I should check?

Bump =)

I was of the same mind that the float or sending unit was the culprit but I read somewhere that it is possibly the gauge itself in the dash. I haven't tried to fix it yet so I'm not sure which is the problem.

Its like bump steer, but with spontaneous vanishing of flammable liquids instead.. Veeerrrryyyyy interesting!

Disregard whatever the heck I just wrote, I am running on like.. not a lot of sleep. lol.

Strange. Mine stops doing it religiously at a certain fuel level ( after 80-100 miles) which to me says that it has something to do with something in the tank...

Mine is a 99 as well and it does not read correctly (reaches E a little faster than normal) until I use the AC, then it reads correctly. So it has lead me to believe that the problem lies in the circuit board with the speedo and such, but since it is a passive problem and I have a Scangauge, I chalk it up to just let it be.

If you do pursue it further, do a DIY write up BFAD style.

the first step is replacing the sending unit which last time i looked cost about $100 in parts and required you to drain and drop the tank. But in the end you do gain 1 gallon in useable fuel as a result of the new sending units longer pick up.

The second part of the TSB is recalibrating the gauge to the new sending unit. You might try this first to see if works. I ended up using the inaccurate gauge in my 3G as an excuse to purchase a ultragauge. Which recently took a ****.

I would also agree that if it's happening at the same spot, that it's your sender. Start there.

Thanks for the replies.

I have done the calibration to no avail. That just made it stay on full for a little longer.

To check the sending unit, lift up your rear drivers side seat, lift the carpet, and you will find an access panel. There you can check the sending unit and the gauge.

Go here

The important stuff is on pages BE-51 and BE-52

Note how to test the resistance of the sending unit, and how to check the gauge.

INSPECT FUEL SENDER GAUGE
Measure the resistance between terminals 1 and 3 in each float
position.
Float position: mm (in.) Resistance (Ω)
F: Approx. 39.4 (1.551) Approx. 184Ω
1/2: Approx. 56.0 (2.205) Approx. 97Ω
E: Approx. 148.9 (5.862) Approx. 12Ω


Good Luck!

I also wanted to post up this information as it seems to contradict the manual that I just cited in my previous post.
According to THIS website,



The caption says this,
"INSPECT FUEL SENDER GAUGE
Measure the voltage between terminals 2 and 3 for each float position.
If resistance value is not as specified, replace the sender gauge."

Now, this is NOT correct, because it says to measure the VOLTAGE, then talks about resistance. Typo....maybe.

BUT the values in this chart are greatly different than the values I posted from the FSM info found at http://www.ncttora.com/fsm/1996/SIL/...ommet/insp.pdf.

I am unsure as to which procedure is correct.

Does anyone know which procedure is correct????? One site says to measure pins 1 & 3, the other site says pins 2 & 3, and the resistances differ greatly.

I am confused.

I had this problem before, too.

Here's the fix from my build thread:

In my case, according to the TSB, I already have the updated board in the dash. The problem I have is the two different instructions I have found for testing the sending unit.

from that portal? stealer told me id have to pull the tank.

The gauge in my 96 does the same thing pretty much. It shows full, then itll drop to empty, (I dont ever get the fuel light though until its actually empty.) But anytime im driving, the gauge is all over the place!! Once I actually come to a stop, and sit, itll read accurate til I start to move again.