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Fuel gauge acting erratically


bachdog
09-02-2003, 11:01 AM
Hi,

This is my first post on this forum and I'm hoping I can get some help.

I have a 1997 Lesabre and recently the fuel gauge started acting erratically. On occassion the needle jumps to full and then drops back to the correct level (at least I think it's the correct level). It usually happens shortly after starting up the car. My wife has been driving the car more than I have and she says that sometimes the gauge jumps around to different levels while she's driving, not necessarily goes all the way to full. At other times the gauge seems to act normally for days at a time.

I called a local dealership and they said they would run a diagnostic to see what code comes up. They charge 1 hour time, which is $77. They and I suspect is could be the fuel sending unit, which according to them is in the fuel tank itself and costs some big bucks to replace because they have to drop the fuel tank.

Does anyone have any suggestions for troubleshooting the problem? Could it be a loose or damaged wire? How hard is it to drop the fuel tank and what about safety issues related to fuel? The dealership said that I should bring the car in with as little gas as possible (of course with an erratic gauge that's not comforting to try to take it down low), because they have to pump it out. Could I do this repair myself?

Thanks for any help you can provide.

GMMerlin
09-02-2003, 11:08 AM
Most likely it is the in-tank sender that is at fault. There is a coating on the sender that wears off and causes the gage to read erratically.

I would recommend that a trained technician do the job for enviromental and safety reasons.

bachdog
09-02-2003, 01:20 PM
"Most likely it is the in-tank sender that is at fault. There is a coating on the sender that wears off and causes the gage to read erratically."

A coating on the sender wears off? I've never heard of a problem like this. Is this typical of all Buick cars? Will the replacement sender have the same problem?

For argument sake, lets say I tried to tackle this job myself. First of all, is there any way for me to verify that the sender is causing the problem? Any possibility it could be something else? Loose wire? Faulty gage? Next, what would I have to do to remove the gas tank.

I assume the following steps would be needed:
1) disconnect the negative cable from the battery
2) relieve the pressure on the fuel system by opening the fuel cap and leave it open until done
3) drain the fuel somehow (please elaborate)
4) remove the tank somehow (please elaborate)
5) replace the sending unit
6) reverse the order and put everything back

Thanks for any additional info you can supply.

tman
09-02-2003, 02:02 PM
I'm having a similar problem on the park ave, except the fuel guage jumps to the three o'clock position. Alsom, when I brake slightly hard, and turn to the left, the car stalls. I'm worriend about both problems, any help is appreciated.

Flatrater
09-02-2003, 08:34 PM
TMAN I bet your problem only happens when you are below 1/4 a tank of gas!! When you have this problem try backing up a hill, let it sit there for a couple of minutes and see if it stalls out. You will have to coast it down the hill to get it started again. I suspect you have fuel starvation!


As for the fuel sender card wearing out!! The card has fine wires on it and over time the wear out. The biggest factor causing the wear out is the fuel acts as a lubrication on the card. Running your tank at a 1/4 full does not lube the card and it wears out faster. Yes you have a bad sender. The sender and be purchased separately.

An empty tank of gas is more flammable than a full tank and it can catch fire on you. Leave the job to someone with experience. All it takes is a small spark or some static electricity to start the explosion.

tman
09-02-2003, 09:22 PM
TMAN I bet your problem only happens when you are below 1/4 a tank of gas!!

Almost, just under a half a tank, whats wrong, and how can I fix it?

Flatrater
09-03-2003, 06:57 PM
Sorry Tman there is no fix for your problem!! It's called fuel slosh, its gas moving around the tank and when the tank is low enough it moves away from the pump starving the pump of gas.

I worked on one Lesabre years ago the only thing that got the owner out of my hair was to put a slosh module or buffer in the sender wiring. All it did was make the guage needle move slower and I also took the sender out bent the arm alittle to make the tank read less than what was in the tank. It only fooled the owner into keeping more gas in the tank which fixed his problem.

GMMerlin
09-04-2003, 11:10 AM
"Most likely it is the in-tank sender that is at fault. There is a coating on the sender that wears off and causes the gage to read erratically."

A coating on the sender wears off? I've never heard of a problem like this. Is this typical of all Buick cars? Will the replacement sender have the same problem?

The problem is not specific to just Buicks, The best way to protect the sender is to keep more than 1/4 of a tank at all times. Gas provides lubercation for the fingers of the sender and prevents premature wear.

For argument sake, lets say I tried to tackle this job myself. First of all, is there any way for me to verify that the sender is causing the problem? Any possibility it could be something else? Loose wire? Faulty gage? Next, what would I have to do to remove the gas tank.

You could hook a variable resister into the wiring for the gage and check the gage movement. The only way to test the sender is to remove it from the tank and check the resistance while moving the sender arm. once the sender arm reaches the bad spot, the ohm meter will read infinante

I assume the following steps would be needed:
1) disconnect the negative cable from the battery
2) relieve the pressure on the fuel system by opening the fuel cap and leave it open until done
3) drain the fuel somehow (please elaborate)
4) remove the tank somehow (please elaborate)
5) replace the sending unit
6) reverse the order and put everything back
You basically have listed the steps needed. If it were mine, I would drive it untill the tank was almost empty then remove the tank. Off the top of my head, I dont remember if your car needs to have the exhaust moved out of the way or not. Basically gas tank removal is pretty straight foreward. Disconnect your fuel lines. wiring connector and remove the retaining straps. Use a floor jack to support the tank while you lower it down.

Thanks for any additional info you can supply.
Most important thing to remember when attempting this is SAFETY!!! Gasoline is flammable and is just waiting for an ignition source. Dont use drop lights and have an extinguisher handy.

rkziegler
03-15-2006, 04:59 AM
I have a 2001 LeSabre with 50,000 miles and an erratic fuel gauge. It seems like it started after I ran out of gas once. I searched every posting for a simpler solution than what you were looking at. How did you eventually solve your problem? Is there a service bulletin or recall possibly? Can a dirty filter cause this? That doesn't seem logical, but wouldn't it be nice if it was a simple maintenance solution, since now I've run out of gas again. I try to use the odometer to keep track, but I'd swear that last tank only got 300 miles, when I thought it should have given me 380??

stuzman
03-16-2006, 12:03 PM
I have a 2001 LeSabre with 50,000 miles and an erratic fuel gauge. It seems like it started after I ran out of gas once. I searched every posting for a simpler solution than what you were looking at. How did you eventually solve your problem? Is there a service bulletin or recall possibly? Can a dirty filter cause this? That doesn't seem logical, but wouldn't it be nice if it was a simple maintenance solution, since now I've run out of gas again. I try to use the odometer to keep track, but I'd swear that last tank only got 300 miles, when I thought it should have given me 380??

I've got a 2000 LeSabre and the fuel sending unit went out. Replacing the sending on your car should be similar. In the 2000 and up models, GM decided to put an accessory panel over the fuel tank to gain access to the sending unit, fuel connections, etc. Take a look in your trunk and remove the carpet and you'll see the panel. Remove the panel and you'll have access to the unit. However, I could not release the tang washer which holds the assembly in. I had to buy a special tool to remove this washer. Maybe, you'll be lucky and can get it off without the tool.

In regard to the sending unit failing, GM had a problem with the sending units failing. Their engineers said that the units were failing because some gas refinering companies were putting too much sulfur in their blend which was creating the failure. The refinering companies said it wasn't so....GM takes them to court and won the case. Now, there is lower sulfur content in the fuel. Also, I understand that GM has redesigned the units to take more abuse. So, who knows....could have been GM's fault all along with therir original design of the sending unit.

dougod
03-24-2006, 11:04 PM
This is a pretty common problem with GM vehicles. I have had to replace the fuel sending units in both my '97 Lesabre and my '01 Silverado. It's not a very cheap repair, but a necessary one, in my opinion.

rkziegler
03-31-2006, 05:13 PM
Well, it was indeed the Fuel Level Sensor. Thanks to www.gmpartsdirect.com (http://www.gmpartsdirect.com) I was able to get them down in price to $99 at the dealer. Labor was $163 however. The part they installed is: GM PART # 25326326
CATEGORY: Fuel Tank Meter Sender/Connector
PACK QTY: 1CORE CHARGE: $0.00
GM LIST: $156.61
OUR PRICE: $78.31http://www.gmpartsdirect.com/images/add_to_cart_btn.gif (http://www.gmpartsdirect.com/results.cfm?addtocart=1&addpartnumber=25326326&singlepart=1&partnumber=25326326)DESCRIPTION: SEN KITThanks for all your input.

Smith1000
04-02-2006, 09:53 PM
I can offer a few pointers because I had this problem with one of our 97 Lesabres about 2 years ago. Had to put in a salvaged sending unit.

If you want to verify that the problem is in fact the sending unit, you can do so by buying a cheap pack of variable resistors from Radio Shack. A miscellaneous pack is about a dollar or 2. The gauge in this car measures from 0 ohms (empty) to 240 (full) (if I remember correctly). Half tank is right at 120 ohms. Substitute the variable resistors for the sending unit wire and check the gauge. The connection can be made at the tank connector. Have to crawl up under the tank to get to the wires. With 120 ohms, it should read a half tank on the gauge. 60 ohms should read a quarter tank, etc. If that works, you know it is the sending unit. You may have to twist 2 or more resistors together that sum up to the ohms you need for the test.

The signal goes through the ecu. From what I understand, only reason it goes through the ecu is to buffer the resistance signal to compensate or slow for tank slosh. So, your gauge doesn't slap back and forth. The other reason is to compensate for the shape of the tank as far as reading full to empty.

The gas tank is fairly easy to drop in this car. Try to ensure that it is low on gas when you drop the tank. You have to drop the exhaust first which is also simple because of the way it is put together. The bolts are removed from the rear hangers to lower the exhaust at the rear. It can be moved to one side very easily in order to lower the tank. Tank only has 2 straps to remove. Before the staps are completely unfastened, you have to remove the fill tube and fuel line. The fuel line is pretty straight forward. It is a clip near the filter. Let the gas run into a coffee can. The fill tube is tricky because it is kind of hard to get to and has a breather line. From what I recall, dealing with the fill tube was the hardest part.

Another thing to check first is to make sure it has a good ground. It probably does based on the behavior of the gauge descirbed. My was doing the same thing.

Sending unit and fuel pump is all one piece in this car. At least they sell it all as one piece. So, it is very expensive. Have to tap the ring with a screwdriver to get it to release. The old unit comes right out. I put in a salvaged one for $75 and that fixed it. The new ones were about $300 or more. I read somewhere that a certain type of gasoline would corrode some of these sending units. The one I replaced was not corroded. It was just a cheap plasticy deal that had a lot of play in it. For whatever reason the variable resister (slider) wasn't reading right.

kflan1375
08-10-2010, 10:13 PM
after market fuel gauge flops all over while driving ,difficult top keep tabs on level . what do later mmodel car use to correct eratic readings/ Some kid of resisterb module ?

HotZ28
08-11-2010, 09:37 PM
after market fuel gauge flops all over while driving ,difficult top keep tabs on level . what do later mmodel car use to correct eratic readings/ Some kid of resisterb module ?
This post is seven years old! :disappoin For best results, try responding to something more recent!

dpalomaki
08-14-2010, 09:55 AM
See the "Fuel Gauge Unreliable" thread for my recent experience replacing the sender in a '04 LeSabre
http://www.automotiveforums.com/vbulletin/showthread.php?t=1037698

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