Gas gauge components - Maintenance and Repair Forum

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Gas gauge components
Monday, August 15, 2016 8:57 AM

So I know this has been discussed before - even by me. Up until now my problem has been every once in a while but it has worked like it should about 95% of the time with a few exceptions always associated with filling up and it always has resolved itself within hours. Something totally different happened to me yesterday - under totally different circumstances.

I was driving a consistent and calm 75 mph on the interstate with about 1/4 problems. Then all of the sudden the check gauges light comes on and the needle drops to empty. I figure I'll fill up and see if that helps but there is no change. So for the last 24 hours, every time I start the car, the needle goes straight to the top (never stopping or staying at the actual, real level) then after about 5-10 seconds, the light comes on and it slowly drops to the bottom and stays there.

So my question is - what are the potential failing/faulty components that are in the mix for this situation? I know there's a sending unit but is there also a level sensor or is that the same thing? Nothing easier to get to or deal with outside of the tank area like a fuse, sensor or wire/connection? I don't know how much it would cost to have the tank dropped to replace the stuff there, but I am guessing a lot more than I can afford.

It's a 2001 Cavalier 5-speed 2.2.

I know hardly anyone reads this forum anymore, but thanks for any replies.


Re: Gas gauge components
Monday, August 15, 2016 10:16 PM
I will say I am not 3rd gen savy but I will explain a few things.Typically when a fuel gauge reads full but it really is (not) the fuel sending unit is or has a bad spot on the fuel sending unit.The simple way to Verify if your fuel sending unit is going bad is not hard to do with your year model.The fuel pump and sending unit are easy to get to.You simply remove your back seat rear cushion bottom! To verify if the fuel sender for the guage is working correctly is to remove the ground wire on top of the sending unit and clean and then scuff up the metal for a good ground on the sending unit metal.Turn your key ON but do NOT crank the crank car.IF you ground the fuel sender ground wire it should peg the empty spot on the gauge.If you do the same and it pegs the full spot your sending unit for the gauge on the fuel sender is bad.Granted unless your cluster itself is having some electrical issue's that is a touch beyond my personal scope.I on my old 85 fuel gauge read full but not even correct!!! I had on my 1st gen had to drop the tank because of the design and if you have to replace the sending unit do the fuel pump at the same time!!!!!!

Re: Gas gauge components
Tuesday, August 16, 2016 6:40 AM

Hmmmm. This is the first I have heard to being able to get to any part of the top of the tank from under the back seat. Sure that isn't a rumor? I'd hate to rip my seats apart only to have to drop the tank anyway. But if it is true, that is a real game changer as I would definitely give it a shot.

I guess I will search around for what I can find online.

Anyone else know about this back-seat approach?
Re: Gas gauge components
Tuesday, August 16, 2016 9:16 PM
I need to correct myself on checking the fuel sending unit procedure.You have to use say a multimeter probe in the sending unit wire that feeds the signal for gauge and stick it into the terminal and then (ground the opposing end) to metal.If the gauge reads full that indicates a bad sending unit in the fuel tank.If it goes to empty that indicates a bad gauge or maybe a cluster problem.My goof.I would just do some simple searching on Here for fuel tank removal and see what comes up.I thought for sure on the 3rd gens the fuel sending unit and pump components were removable by taking out the back seat lower cushion.As I said I am Not 3rd gen savy just mechanically inclined.

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