nitrotang

iTrader: (2)

Has anyone had any issues with their fuel gauge? I just filled up today since my gauge said I was less than 1/4 full. But the pump only filled up 10 gallons. I turned my car on and was about to drive away but noticed my fuel gauge still said it was less than 1/4 full. I swiped my card again and thought there was something wrong with the pump. When I tried to fill more gas, it kept stopping since I'm assuming my tank was already full. I tried to drive it around to see if maybe the fuel level sensor was stuck but even after parking and turning the car off and on several times, the fuel gauge is stuck there. Now it seems, every time I start my car, the fuel gauge drops a little bit despite just filling up a full tank of gas.

bclexus

That's a new one - I haven't heard of anyone with that issue.

nitrotang

iTrader: (2)

I know right?! I tried searching everywhere to see if anyone experienced anything similar but found nothing. To add to my observations, I noticed that every time I start my engine, the fuel gauge drops a little each time. Makes no sense!

medsaver

My wife said this happened to her twice but I wasn't with her and can't replicate it so I'm not sure if it was her or the car.

waygreen

If bc hasn't heard of it it probably hasn't surfaced on this site before.

That said, similar issues are common on older Chevy trucks ('06 and earlier). The fuel level sensor develops voltage issues and needs to be replaced. Keeping the fuel above half seems to help alleviate the problem but it is inconvenient for sure unless you learn to rely on your odometer. The problem is that you need to drop the tank to get access to it before you can even test it. I'm not sure but perhaps you'll get lucky and find our cars have an access port under the rear cushions or in the trunk that will make things much easier.

Overall, do you notice any other electrical gremlins? How old is your battery?

nitrotang

iTrader: (2)

I haven’t noticed any electrical problems aside from this. I purchased it used 2 months ago and had a reputable shop I’ve always brought my car to check everything and it checked out fine. So I’m not sure how old the battery is. It’s definitely not OEM.

Would an old battery cause this kind of an issue? How do I access the fuel electrical stuff from the trunk/backseat?

jonathancl

Well, the fuel level sensor appears to be a mechanical float, part of the fuel pump. The 2GS pump assembly was very similar.

It is possible that something mechanical is amiss.

waygreen

I have not owned this car long enough to learn its quirks. Because it's a Lexus, I don't expect to have many, anyway

But one of my previous rides was an e90 series BMW. They were notorious for electrical gremlins caused by old, dying batteries. Whether that is true with the GS is not something I know. I was simply asking in order to get an additional data point. In those cars you could also gain access to the lift pump or lpfp but removing the rear seat. I just looked in my manual and it seems to indicate there is an access port in the spare tire well. That will save the aggrevation associated with draining and dropping the tank to test or swap the sending unit, which appears to be available by itself and not completely integrated with the pump.

YaMomma

Fuel pump access panel is under the rear seat you don't have to drop the tank.



According to the repair manual it appears the sending unit is attached to the fuel pump.

john341

does the GS have a way to diagnostic mode for the instrument cluster? I will check the Gauge first before removing the fuel pump also does you Range indicator change after filling the tank?

bclexus

I'm guessing you will ultimately be better having Lexus diagnose and repair whatever is causing this problem. You can waste a whole lot of time and money trying to figure out what's wrong...and still not fix the problem.

YaMomma

You can test it with Techstream (GTS) which will show you what the fuel level sending unit is sending so that you can compare it to the instrument cluster. The range indicator should change after filling the tank.

nitrotang

iTrader: (2)

Thank you everyone for all your suggestions and thoughts! I had some time today, so I decided to investigate myself to see if I could make determine anything. After removing the backseat cushion and checking first the driver side one, everything looked fine. However, when I checked the passenger side I noticed after removing the black service hole rubber gasket thing, there were two wires, a red and white wire, and the red one had been severed. Furthermore, I pulled out a bunch of white fluff material. Is that stuff supposed to be there?! There was none of that fluff on the driver side. I tested to see if the severed red wire was the culprit to my incorrect fuel gauge reading, so I tried to bridge the connection. When I turned on my car, the fuel gauge needle went back to where it should be! BINGO!

So I guess my question is, has anyone else had this issue? And would anyone be willing to open up their passenger side to see if they have any white fluff in theirs? If it is some sort of short circuitry that burnt the connection of the red wire, that definitely could've been a fire hazard, specially with all that fluff material in there! Maybe everyone should check theirs to make sure that red wire is still insulated.

chinee

My guess is that you have a critter making himself comfortable with nice fluffy bed. Where do you keep your car parked?

waygreen

Nice work, OP. I love the satisfaction of finding and fixing problems. I won't be able to take a look until next weekend but I will search for fluff and report back. I would have expected burnt or melted plastic if it was electrical but electrical issues are my weakest subject so my opinion is of little value. It may well be a critter. Can you look down the hole to see any shavings from them gnawing on it? The only other thing I can think of would be sloppy assembly although the pics don't quite seem to jive with that.