Fuel Gauge Stuck on Empty

[fawcett_chad]

Fuel gauge fixed!

After getting the estimate from the LR service center, I had a renewed resolve to replace the fuel level sensors myself. A couple weeks ago I ordered the parts I needed from Amazon - all in just around $130. Since then I've just been burning down my gas till I was as close to an estimate of empty as I could safely be. Finally had the chance today to take on the project. I got the tank removed, which is quite a job by itself, and got all the hoses and cables disconnected. Then I got the access port open and removed the fuel pump from the harness and turned it so I could access the rear sensor. That was a pretty easy replacement. After that I took on what many have called impossible. I reached in to the tank with my left arm while kneeling on the passenger side of the tank. i reached down up to my elbow and was able to pop my elbow in the hole while starting to bring my forearm towards the front of the tank. At first I got stuck, but then was able to push my elbow down far enough that I could reach around the inner frame and just barely reach the front sensor. I am 5'9" and I think if my arms were a little longer it would have been easier to reach, but at the same time, then it may have been harder to get my arm in there in the first place. For some people this job may be impossible, if you are too tall or too short.

So I can give more details if you want, but I got the thing back together, powered up the car and the gauge rose slightly, but was still on empty because there was only like a gallon of gas in there. I drove to the gas station, filled up and voila! the gauge immediately went to full when I powered her up! Victory!

The bad news: after getting home from the gas station and celebrating with a nice cold beer, I looked underneath and found a slow gas leak... Guess I'll be under the car again tomorrow figuring out which fitting isn't tight.

 

[crayonsun]

Hi, a new member here.
I bought 2006 LR3 recently and it came with fuel gauge malfunction.
Thanks to fawcett_chad's information, I was able to look at the right place.

I tried usual stuffs (disconnecting battery, ODBII code check etc) first, but no fix.
I took a deep breath and dropped the tank. I first checked resistances on both senders before trying to reach either of them. The rear one’s resistivity looked like within a normal range, but the front one showed infinity which means either the sensor is dead or disconnection somewhere. My arm's not buff and I am not tall or short either so I went ahead and tried to reach the front sensor. Just like fawcett_chad, my elbow got stuck, but after a few tries I was able to reach the sensor. I borrowed an arm cover from my wife and it helped a lot. It turns out that the part of sensor that I can detach from the tank frame is toward the rear. I was able to take out the sensor and had a better look. Checking the resistivity, it was still open. I disassembled the plastic enclosure of the variable resistor. I found out that the variable resistor itself is fine. It was just a green wire near the soldered part got deteriorated. I pulled the green wire from the board and the metal wire just came off the plastic housing. Once I temporarily connected again, I was able to read the normal range of resistivity.

I thought I could simply resolder the wire, but the metal contact on the board was gone. I tried flux on some exposed copper, but no help. I decided to just order a new sender and started to reattach the fuel tank. Before I close the cap of fuel tank, I looked at the plug for front sender and thought maybe I can fool the computer by putting some resistor, at least until I receive a new front sender cause I hated to see any warning light on the dash. Based on the service manual, the front sender should be around 50 ohms when fuel is low. So I figured that I will try 50 ohms. In fact, I started with variable resistor to experiment, but soon my battery died. Well, I am going to order a new sensor any way. So I pulled the front sender wires from the plug and I put 50 ohm resistor.

I thought, having front sender showing almost empty, I would see a half tank from the gauge when I filled up the gas tank. But amazingly, it showed full tank. I drove about a week until I used 20 gallons, the fuel low warning light showed up. Constantly checking MPG and the mileage, it seems to be working just fine so far without real front sender.
I am holding up ordering the part for now.

 

[fawcett_chad]

Glad my post could be helpful. I'm not sure if I follow you...you're fuel gauge is stuck on full now but gives a warning light when it's low?

I don't know what they are running now, but the front sending unit was about $60-70 from Amazon when I replaced it. I bought both because I wasn't sure which one was bad and it was a relatively cheap part. Because you know it's the front one, you could save yourself some money and just replace that one.

Congrats on the Lr3 btw. I actually ended up trading mine in shortly after fixing this issue. Got a 2011 Xterra pro-4x. Definitely a downgrade in a lot of ways, and I still miss my lr3, but I don't miss that feeling of wondering what's going to break next.

 

[crayonsun]

Thanks again, Chad.
When I found out my front sender was dead, I thought I might have to get a new tank in worst case, but I knew the front sender was replaceable reading your post.

To clarify, the gauge isn't stuck on full. I meant it showed full when I filled up the tank. The fuel gauge indicates the fuel level correctly. I am happy that the fuel gauge operates how it supposed to, but it puzzles me how the car figure this out. My understanding about having two fuel level sensor is to compute the average of two sensors. But with the front sensor sending the low fuel level all the time, fuel gauge is just showing the level based only on rear sensor. It defeats the purpose of having two fuel level sensors.

Any way, congrats on your Xterra, it surely is another solid SUV. I heard that Coloradans buy Xterra 3 times more than national average.

 

[Dynamite_Goat]

My son and I just tackled this today on our 07 LR3. What a PITA but very satisfying to have it done. I never would've figured it out without this helpful post!

 

[Globetrotter]

Reading the fault codes will tell you if it is a sending unit. It will say either unit 1 or 2. If it is a grounding failure the gauge will not say empty but give all sorts of funky readings accompanied by random check brake pad warnings.

A complete new fuel tank with the front sensor installed runs about $800 and a couple hours labor to install.

Mine has a similar problem and just checking connections. Which is sensor 1 and which is sensor 2

 

[Trynian]

I can't remember for sure but I recall 1 is front and 2 is rear. It has been awhile but I think the actual sensor says 1 or 2 on the module itself so someone who has replaced one recently might be able to chime in and look at their sensors.

As to the fix by Crayonson I think what will eventually happen is if you are pointed on a steeper down hill for a period of time you will get a temp sensor fault and the gauge will go to empty. Not a big deal as it will come back when leveling out. When my rear sensor was off showing empty even when full, if I was pointed uphill for to long it would fault and drop to empty until I leveled out for a few minutes.

 

[Globetrotter]

Thanks for the info. Well I removed both front inner wheel arch trims only to find there are no connectors there - well it allowed me to clear the muck out before putting them back.
So where is the connector that the fuel sensors go through on the way to the gauge. I thought I could measure the resistance at this 'magic' connector and see what the problem is

 

[Trynian]

I believe the connectors you are looking for are on the right side behind the wheel well splash guard, right up against the body they are pretty obvious.

 

[Globetrotter]

Trynian, Had a good look around after taking out the wheel arch lining and found 'nothing' resembling a connector. Anyone have a picture of what I am looking for.
The vehicle is a 2007 discovery 3 but the vin indicates 2008 model and the build indicates 2007, hope that makes sense.