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"jumpy" fuel gauge


notAwimpala
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Hey guys and gals, I'm new on here and I have a question for you. My fuel gauge has been acting up lately and has been going up and down a lot. I have no idea what the problem is. The car could be on a perfectly flat surface and go all the way down and the low fuel message comes up on the display. I thought I'd ask you W body guys since I am not as knowledgeable on Ws. I could probably search but I am too lazy. :D

 

Any input is greatly appreciated before I try strolling down to the dealer and chucking my money down the toilet for them to just "take a look at it". :wink:

 

Forgot to mention I have an 01 Impala LS w/L36

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before you go that far, check the conector near the fuel tank. take it apart and make sure there is no crap in there and its not loose. given the age of your car i would look for production type mistakes before worn or bad parts

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before you go that far, check the conector near the fuel tank. take it apart and make sure there is no crap in there and its not loose. given the age of your car i would look for production type mistakes before worn or bad parts

 

On a four year old car? Production screw ups happen in the first 5k miles.

 

If your car came into work.....and the gauge moved around.....I would put a fuel level sender in it.

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before you go that far, check the conector near the fuel tank. take it apart and make sure there is no crap in there and its not loose. given the age of your car i would look for production type mistakes before worn or bad parts

 

On a four year old car? Production screw ups happen in the first 5k miles.

 

If your car came into work.....and the gauge moved around.....I would put a fuel level sender in it.

 

you must work for a dealership?... :roll: ...am i right!?...

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Yeah........I've seen it enough times to ensure that its the problem.

 

As long as the problem is indeed described as I make it out to be. I'd have to see it to be sure.

 

The reason I am so sure of myself...is, well, I know how the system works. The float in the tank is attached to a set of fingers that ride along a big resistor type strip. The fingers wear off....causing the voltage being sent to vary.......causing the gauge to jump around like it does.

 

The only way to be sure of this is to pull the fuel tank down, pull the pump out and look at the sender.

 

You might be trying to accuse me of shotgunning parts. Thats fine.

 

But whats it pay to do that? I only get 1 hour for diagnosis. I'd like to remove the fuel pump and check it out.....but what if the customer doesn't want to buy the level sender after all that work? I just went though all the effort of removing a fuel tank for 1 hour.

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at least your problem you can fix, on most of our cars, if the gas guage gets anywhere from empty to a half a tank, the needle moves around so much when I turn, accelerate, or decelerate :lol: I cant tell how much gas I have.

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at least your problem you can fix, on most of our cars, if the gas guage gets anywhere from empty to a half a tank, the needle moves around so much when I turn, accelerate, or decelerate :lol: I cant tell how much gas I have.

 

 

Don't feel bad, like I said...I have a mid-90's GM, I know EXACTLY what you mean. What I love is when you have above quarter tank and go down a steep grade for a few miles and the "Check Gauges" light comes on because its on "E" :lol:

 

 

Aaron

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Eurosport94 wrote:

at least your problem you can fix, on most of our cars, if the gas guage gets anywhere from empty to a half a tank, the needle moves around so much when I turn, accelerate, or decelerate I cant tell how much gas I have.

 

 

Don't feel bad, like I said...I have a mid-90's GM, I know EXACTLY what you mean. What I love is when you have above quarter tank and go down a steep grade for a few miles and the "Check Gauges" light comes on because its on "E"

 

I feel bad for other that have this problem, just the other day my mom was driving my car and she ran out of gas and my brother in law had to take it and fill it up for her. Not fun.

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The reason I am so sure of myself...is, well, I know how the system works. The float in the tank is attached to a set of fingers that ride along a big resistor type strip. The fingers wear off....causing the voltage being sent to vary.......causing the gauge to jump around like it does.

 

I don't mean to nitpick, but these systems are based on Ohms, not voltage. You don't want a live wire in your tank :devil:

 

0 ohms= no gass

 

90 ohms= full tank. (and heavy) 16 gallons x 7lbs/gall= 112 lbs

 

When that wiper slides over the copper windings on the fiberboard, it's more likely the windings will wear before the wiper/contact will.

 

NEVER-NEVER-NEVER suggest that someone drop the tank first before checking something as simple as that connector. God forbid it is that connector.....then many hours later and at least a couple bills will have been wasted.

ALWAYS check the cheap and easy items first!!!!

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Well.....I do mean to nitpick......because it actually IS voltage.

 

Well a 5 volt referance signal gets set to the tank......there is a voltage drop accross the resistor.....if the PCM sees low voltage the tank is full....empty voltage will be nearly 5 volts. So if the level sender is completely shot (open)....the gauge reads full.

 

Besides....your resistance is wrong anyways. On newer cars and trucks (like this 01 Impala) 230 ohms is full and 40 ohms is empty.

 

Trust me......the contacts/fingers DO get bent/broken/destroyed (doesn't really matter anyways..as in either case it has to be replaced). I don't know what you do for a living....but I see these things everyday....and it happens.

 

You can check your connectors all you want..........but a bad connector does not show up like this. Hell......if a level sensor doesn't fix his problem, I'll buy the parts for him.

 

 

 

 

To replace it.......you have to drop the fuel tank down (best if its nearly empty ;))......pull the pump out and pull the sender off of it. Its a couple of clips and an eletrical conector or two.

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you must work for a dealership?... :roll: ...am i right!?...

 

no but i used to be a test tech for an elecronics production factory. im an electronics tech now and thats always how i start, you look for simple stuff before you get into replacing parts. you probably get 50-75 bucks for that hour 150-300 bucks for the sender, but thats not bad when your on the receiving end.

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you must work for a dealership?... :roll: ...am i right!?...

 

no but i used to be a test tech for an elecronics production factory. im an electronics tech now and thats always how i start, you look for simple stuff before you get into replacing parts. you probably get 50-75 bucks for that hour 150-300 bucks for the sender, but thats not bad when your on the receiving end.

 

well, that comment was not actually directed towards you!...it was more towards the "JUST CHANGE THE SENDING UNIT" because, i know how dealers work...they just change parts...don't actually look over the situation first...they are just out to sell parts and make money... :wink:

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Well.....yeah, I am out to make money....jus like everyone else.

 

Still don't think thats whats wrong, eh?

 

actually, you made pretty good points about why you think thats it...i'd check things over first...look for something obvious, if i couldnt find anything...i'd change it like you said...i'm not saying your WRONG... :wink:

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