Fuel Gauge False Reading please help!!!

my fuel gauge isn't reading right. when i get to quarter tank i fill up emidiately because after it passes that mark i can't tell if the tank is empty or not .

Some times the car shuts down for gas and the needle is just below the quarter tank mark. sometimes it shuts down before the gas light comes on. it has embarrassed me on many occasions in the middle of town where i had to push my car out of the traffic and get a gas jug to refill .

what do you guys think is the problem?

You have two level sensors in your fuel tank. One or both of them may be faulty. It's also possible that the pump that keeps the levels uniform on both sides of the tank is faulty.

Your Bentley repair manual will show you how to check the function of the level sensors, and it should also show you the location of the pump.

thanks for the info GP, but is this a do it yourself project or should i check my mechanic?

Originally Posted by deezem

thanks for the info GP, but is this a do it yourself project or should i check my mechanic?

If you are a reasonably competent DIYer and you have access to a well-ventilated work space that contains no open flames, pilot lights, or other sources of ignition, then replacement of the level senders should be no big deal. Be sure to do some simple diagnosis first to make sure that they're really the problem. A special tool is needed to turn the big locking ring on top of the sender, but some DIYers have improvised with hand tools.

As for the pump inside the tank, I've never replaced it, so I have no idea how hard it is. Perhaps someone else who has replaced it can tell us more.

Read the wiki and use the secret OBC functions.

I have the same problem but I don't go under 1/4 tank.

Before getting involved in real repairs, dump a bottle of fuel injector cleaner in your fuel tank. It may clean your sending units enough to get them working again. The chances of success are only about 50%, but the cost is very low. Redline, Chevron, and others make good fuel injection cleaner.

same problem here. i just keep it over 1/4 tank at all times. don't be too embarrassed about having to push the car out of traffic until you've had it towed to a shop for 2 weeks because it was out of gas!!! (see my thread on that one). Hope it makes you feel better!

Originally Posted by kgrosse

same problem here. i just keep it over 1/4 tank at all times. don't be too embarrassed about having to push the car out of traffic until you've had it towed to a shop for 2 weeks because it was out of gas!!! (see my thread on that one). Hope it makes you feel better!

I am ashamed to say it but i laughed my ass off at your thread. it feels better to know that i wasn't the only one that got duked by this problem. but i still think i bested you on the embarrassing meter when this one time i shut down in the middle of town on a busy day and my mom jumped out the car and abandoned me to the angry traffic that piled up behind me and hecklers standing on the sidewalk
she was like "honey, sorry to do this but call me when you get the car running again..."

Originally Posted by alpinweiss

Before getting involved in real repairs, dump a bottle of fuel injector cleaner in your fuel tank. It may clean your sending units enough to get them working again. The chances of success are only about 50%, but the cost is very low. Redline, Chevron, and others make good fuel injection cleaner.

i will definitely try this and if it doesn't work i will call in my mechanic. thanks

Originally Posted by G. P. Burdell

If you are a reasonably competent DIYer and you have access to a well-ventilated work space that contains no open flames, pilot lights, or other sources of ignition, then replacement of the level senders should be no big deal. Be sure to do some simple diagnosis first to make sure that they're really the problem. A special tool is needed to turn the big locking ring on top of the sender, but some DIYers have improvised with hand tools.

As for the pump inside the tank, I've never replaced it, so I have no idea how hard it is. Perhaps someone else who has replaced it can tell us more.

thanks for the advice but i don't think my DIY skills are ready yet to handle this one. maybe if there was a vid on youtube i'd try it.

if the injector cleaners don't work then i'll call the mechanic

thanks

Originally Posted by deezem

i will definitely try this and if it doesn't work i will call in my mechanic. thanks

I know this is an old thread but but it seemed pointless for me to start a new one. I've been having the same problems for months.

Just wondering if you tried the Fuel Injector Cleaner and if it worked.

I'm having a somewhat similar but different problem.

So far, this has only happened when I fill up. The fuel gauge won't show full (even though I just put in 15 gallons), but about 1/4 or 1/2. I'll shut down and then start up again a few times. Then, after a few times, it will finally show the correct fuel level. It will be fine until I fill up again.

This has only happened twice now. Doesn't happen at any other time. No other false readings that I've noticed.

Could it be faulty sensors?

Also, FWIW, I just put in a bottle of fuel injector cleaner about a month ago. Not sure if it's just coincidence or what.

Anyway, any input would be appreciated.

Thanks!!!!

Johnny

Please post if you solve this riddle. I replaced my son's fuel pump on Friday and the fuel gauge malfunctioned immediately
Tank had a little less than 1/3 tank before. After the change the tank read zero. Filled the tank and it came up to 1/2 tank. Drove around on the weekend to get the fuel down and pulled the pump out again. The level arm seemed to rub and not go up and down easily so I worked on it till it moved easily. Iwas convinced that I had solves the problem. However when I filled it the gauge read between 1/4 and 1/2 a tank. Checked hidden codes whixh read 24.0 litera on the left side and 0 liters on the right side. How can I test the wiring to the gauge pump? Also has anyone tried swinging the level sensor when it is out of the tank to see if it changes the tank gauge reading?

Originally Posted by Solidjake

Read the wiki and use the secret OBC functions.

I have the same problem but I don't go under 1/4 tank.

+1 i treat 1/4 as the reserve, just to be safe, its good practice

I seem to have the same issue but I've noticed my gauge is about an 1/8 off. since it's just a small amount I fill up at a 1/4 tank, which is what I have been doing for years in all my cars.. so it's no big deal but it would be nice to have it accurate.

These threads might help.
- Decent Techron "soap for gasoline" thread (1) & how to clean your gas gauge sending unit (1)

They're from the E39 bestlinks, but, the sending unit & Techron is probably the same for the E46 ...

Techron Concentrate Plus not only helps clean combustion chambers and fuel injectors, it's also the only fuel system cleaner that can actually help remove silver sulfide deposits which corrode sensitive fuel sending unit sensors. This corrosion can happen from regularly filling up with lower quality gasolines. Eventually, the silver sulfide buildup can lead to faulty fuel gauge readings, which can be mistaken for a broken sending unit, potentially costing hundreds of dollars in unnecessary repair bills. Many times, all you need is one bottle of Techron Concentrate Plus to help fix the problem.