gas gauge problem?

[p nut]

My gas gauge said 1/2 full when I pulled in yesterday, which made sense, because I'd gone about 160 miles since the last fill up. This morning when I started it up, it said almost empty and the gas light was on. I was confused, and thought maybe someone syphoned the gas overnight (didn't put her in the garage last night). I drove around for a bit and noticed that the needle was slowly moving up. And continued to move up until it was again almost at half way point.

Anyone had this issue before? My old 98 had another issue with the gas gauge where it fluctuated constantly (by about 1/8 of a tank), but nothing like this. I filled up again today and it seems to be back to normal. Weird.

[Peter]

This is an obvious question but one to ask regardless - do you park on an incline?

My gauge has been giving me issues as well. When I first got my truck the first quarter tank would go for about 75 miles. My latest look showed something like 31. I still get the same mileage but for some reason the needle doesn't like to hang out at the top of the gauge.

[p nut]

I do, but I have not had any issues until now. It's not an extreme incline either.

[BruceTS]

kind of normal problem with the sending unit in the 3rd gens, especially the 99's...

When i had my tank out I cleaned the contact surface that the wiper arm slides against and all the issues I had went away....

[Robinhood4x4]

Seems a bit early for a 2002 to have fuel sending problems, but it could be.

This is what my 93 fuel sender looks like and I'd imagine a 3rd gen looks similar or at least works on a similar concept.

http://www.robinhood4x4.com/gallery2/Rear%20Leaf%20Swap/images/IMG_1457.JPG

The float on the end swings up and down while the arm wipes across a resister. As the arm moves the resistance changes, thus telling the gauge how full the tank is. When mine had problems as soon as the gauge reached about 3/4 it would dive toward empty, but when I got to 1/2 tank it would begin reading ok again.

http://www.robinhood4x4.com/misc/SAS%20done/FuelSender.JPG

It can't be seen too clearly in this picture, but at right about the 3/4 mark, the resister was worn through. Essentially the resistance would go to infinity, thus telling the gauge the tank was empty. When I reached 1/2 tank the resister was fine and the gauge worked perfectly again. This tells me for the past 14 years I've been driving around at about 3/4 tank most of the time.

To get to the sender you have to drop the tank. It's not hard, but it helps to have two people.

Oh, and I believe the thimble looking thing with the wire going to it is the sender for the dash light. The wire rests on the bottom of the tank so therefore the sender is about 1" off the bottom.

[mkgarrison5]

out of curiosity considering i have an 02 taco with 90k miles... couldnt you just use a heavily concetrated cleant mixed with fuel help clean it or does something really go bad with it causing the issue?

[4RunAmok]

I'm actually having a different problem.

The gauge is completely wrong ALL the time. And sometimes it will just instantly drop way below E, and the Low Fuel Warning light will FLASH.

This is still happening after replacing the fuel level sending unit AND fuel tank. The dealer assured me that the tank was the problem because I'd dented it while offroading, and this also damaged the sending unit. They wanted $900 to fix the problem. Thanks Bob Smith Toyota!

After buying a perfectly straight tank AND skid plate at the scrap yard for $150 and replacing it myself, as well as a $100 replacement sending unit, it still drops below E and flashes the warning light, although not as often, and even with the new sending unit, it still will not show the correct fuel level.

The old sending unit looks just like the one pictured above, the new one I'm told is the new version, shorter arm, different mounting height, but the float sat even with the old one in the "empty" position while mounting it.

Any ideas?

[Robinhood4x4]

The FSM and chiltons tells you how to use a multimeter to see if the sender is working right. Try that.

[MTL_4runner]

There were 2 TSB's on that exact issue for the 99-00 4runner Fuel Gauge problem.

One TSB dealt with the replacement of the fuel tank sender (TSB # EL010-00 from Aug 4, 2000):
http://www.larsdennert.com/4runner/fuelsender

The second TSB is the fuel sender recalibration (TSB # EL010-99 from Dec 24, 1999):

1. After replacing the meter circuit plate or inclination sensor, move the vehicle to a level location. (A surface with an inclination no greater than 0.5° is the target flatness.)

2. With the ignition switch in the “OFF” position, press and hold the trip reset button.

3. Continue pressing the trip reset button while turning the ignition switch to the “ON” position.

4. Within 5 seconds of turning the ignition switch “ON”, release the trip switch, press the trip switch 3 times, and on the third press hold the switch for 5 seconds. The buzzer will sound for 1 second at 800 HZ.

5. After the buzzer stops, release the trip switch.

6. Press the trip switch one more time and hold for 5 seconds. Once more, the buzzer will sound for 1 second at 800 HZ.

7. The calibration process is completed.

NOTE:
If in the operation of step 6, the buzzer sounds higher than that of step 5, turn the ignition switch to “OFF” position and repeat the setting procedure from step 2.


I would obviously try the sender recalibration first because it's easy to eliminate and then do the TSB replacement sender if that fails (not sure if you bought a new sender at the dealer or a used one, but if it was used you may need the new part from the dealer).Also check the resistances because some have found issues with the sender not getting grounded properly and this in turn affects the sender's fuel level reading to the gauge.

[4RunAmok]

Thanks Jamie!

I performed the recal, hope that works.

The sender is brand new from the dealer. The only thing about the installation that bugs me is the wire harness might not be tucked behind the other wires. I might have to drop the tank and check that out.

[MTL_4runner]

The flashing fuel light is usually indicating it needs a recalibration.
Obviously post back if that doesn't fix it for you (2-3 tank fulls and I'd call it solved).

[tacoclimber]

Hmm.. Sometimes mine in my 03 will drop to almost empty, fluctuate for a few minutes, and then go back to where it belongs. But it only does it once a month or so... Weird.

[JWBehm]

My first half a tank according the gauge goes to about 160 miles then the light comes on around 210. It doesnt bother me though, I just always know to fill up right at 240 miles or so.

[4RunAmok]

The flashing fuel light is usually indicating it needs a recalibration.
Obviously post back if that doesn't fix it for you (2-3 tank fulls and I'd call it solved).


I'm curious when to perform the recalibration? Right after filling up? or right before running out of gas?

I've performed the recalibration 3 times now, and I still does not show correctly.

It was showing needle above F when I was able to fit 8 gallons into the tank, suggesting that the tank was actually only half full.

This is really getting to me, I don't want to take it to the dealer again, they wanted me to spend $900 and the problem would still exist.

[MTL_4runner]

You may need to drop the tank and pull the sender to check it's function.
Sounds like something is still not working mechanically (either the resistor or the vent tube).

[4RunAmok]

Jamie, could you explain the purpose of the vent tube? And how it plays into this scenario?

Thanks in advance.

I feared that I might need to drop the tank again. I hope this is not the case. But I will do what I need to do to solve the problem.

[MTL_4runner]

I could be wrong but I don't think the length of the vent tube plays a very big role in the gas gauge not reading correctly since the reading itself is purely electrical. What I meant was the fact that you had the updated sender installed or not. If I were a betting man your actual issue lies in the potentiometer on the sender or a poor ground which is causing an intermittent signal to the gauge up front. You may be able to test these items without dropping the tank down but it's obviously easier if you do.

[4RunAmok]

It appears that my VIN shows I need to replace the circuit board and the sensor, etc.

Sigh..

[MTL_4runner]

It appears that my VIN shows I need to replace the circuit board and the sensor, etc.

Sigh..


That sucks but it sounds like you found your issue.
Let us know how it goes after the install.

[4RunAmok]

A final update on this issue and kudos for Bob Smith Toyota...

For my particular VIN, the fuel guage sending unit and the printed circuit board in the dash has to be replaced when this issue rears it's ugly head.

This probably should have been a recall item, which would make the replacement free. But it isn't, the parts are listed as replacements of old parts rather than recall.

Maybe it's just me, but when a circuit board fails in one car over time, then it's wear and tear, but when it's in MANY cars to the point that Toyota puts out a Service Bulletin then it is factory defect and justifies recall. In my case, it's a failure of both the sending unit and circuit board.

This circuit board also holds the memory for the odometer, which means you MUST go without the vehicle while they certify that the mileage doesn't change, the part must be ordered with your current mileage pre-programmed.

Well, that's where Bob Smith Toyota here in La Crescenta (I previously blasted them for not dignosing correctly) stepped up and made this happen AS FAST as possible. We were barely without our 4runner.

The fuel gauge works perfectly now.

Now all I have to do is protect the tank from future dents. The dent wasn't the cause of the problem, but I don't need any LESS fuel capacity.