99 Tahoe Fuel Gauge it acting weird

[typicalsituations]

Me again, I forgot to mention this about the Tahoe. When I got it , the gas was half full, then I filled it up... I used that tank, then filled it to the brim. NOW, my gas guage is freaking out. It seems like its acruate, but its moving back and forth VERY rapidly. Its not moving alot, its moving between TWO of the little tick marks, but its moving SO fast that it appears to be BLURRY. Like if you were to hold your hand up and wave REALLY fast. Its reading like it should, but its just moving. Sometimes it moves closer to the FULL when it shouldnt be moving at all. Since this JUST happend after a filled it, Im thinking maybe I overfilled and messed it up? Right now, its close to 3/4 of a tank, but its STILL doing it. Can you swap out JUST the fuel gauge, or do you have to replace the whole Instrument panel? If you do have to replace the whole thing, can you salvage the odometer and put it in the replacement cluster? Thanks for your help!


Ps. I also have the infamous "THUMP" when I stop... Its annoying,

[sprucegoose]

Chances are that it is not your gage itself, but probably the sending unit. It is located in the tank itself, or possibly the wires going to it. It almost sounds like a bad ground, but I am not that familiar with this.

When you said the imfamous thump, are you refering to the drivetrain clunk when you pull away from a stop sign after coming to a stop?

[typicalsituations]

I hope its not the sending unit... It will just have to be messed up if thats what it is.
Yes, I have the drivetrain clunk when I pull away, or stop. I read about greasing up the link between the tranny and the drive shaft. Sounds like that might be a tough job.

[sprucegoose]

On the sending unit in the tank or wiring, I would just do some investigating into that before worrying about it too much. I don't think it hurts your gage, but I'm sure it can be annoying!

As far as greasing the splines on the driveshaft yoke. I did that when I changed out my U-joints, and it came back in a month or so. Have heard others say the same thing. What cured this for me is when I drained the transfer case fluid and filled with the new autotrac II fluid (blue in color, and I believe it is synthetic) from GM. It was about $8 a qt. if I remember right. You need about 4-5 qts.

This for sure would find out if it was done on yours. It sounds like you just bought the truck if I remember right. The drain and/or fill plug was an internal sq. drive plug, and the replacement is an external hex also. That is the one thing that you can see visibly right away that may have been updated. You could open the drain plug slightly to see if the fluid is blue, or the conventional red auto trans fluid.

It is a 2 step process where you drain the old fluid, refill with the new. Drive it for 1-2 hrs and drain and refill again. You will need that cheap pump I talked about to get the new fluid in, as there is no room to pour it in. You do this twice to get as much as the old fluid out as possible. I did this 1 1/2 years ago (36K miles) and mine has been cured ever since. Not sure why this works so differently, but it does. Boy is it nice, that constant bump/chirp was so irritating! I would be willing to bet that that was caused the pre-mature failure of my U-joint there as well...

[surfnobc2]

thommy here ,

99 tahoe 2/d 4x4 5.7 125k

i have the same problem with my gauge it shakes rappidly and i dont know what causes it , i also have a thump sound but mine doesnt happen all the time every once in a while but i have no squealing or anything ill be stopped for a min or so waiting in line or somthing and it will just thump .. also i feel on mine i am losing a lot of power .. i have pipes on mine and i can hear a lot more about my exhaust, so right before my car shifts gears i can hear it hesitating and i have had plugs and wires replaced , was told i didnt have to replace my caps ... but still hesitates really pisses me off ... seems to happen a lot more when my air is on ... i dont know can anyone please help !!!!!!

[jww333]

I to have the same flicker with my fuel gauge. My 1998 GMC Sierra Z71 had 133,000 miles on it when the fuel pump went out. After getting my fuel pump replaced a few weeks ago my gas gauge started flickering. The shop has installed 2 aftermarket fuel pumps and now one factory fuel pump and the gauge is still flickering. If anyone has any answers they would be greatly appreciated.

[wafrederick]

GM does have problems with their sending units and you can get just the sending unit from the dealer.All you need is your insurance slip,the dealer needs the vin to order the part.If you want to buy an aftermarket fuel pump,buy one from Carquest and here is some good news.Carquest did switch to Delphi to manufacture their fuel pumps and did away with Airtex.Found this out recently and it says on the box.Delphi is GM's manufaturer for fuel pumps.

[Cholo Mike]

Hello my name is Mike! In the morning when i start my truck i hear the thump like something is under the 4x4 stick in the center or something. but for last 2 years been trying to figure out my fuel gauge flicker? I don't seem to find anything on answers to this has anyone figured out what there's was? Can anyone be more specific or help me out on where to start besides dropping the gas tank! I hope it doesn't come to this!

[j cAT]

Originally Posted by Cholo Mike

Hello my name is Mike! In the morning when i start my truck i hear the thump like something is under the 4x4 stick in the center or something. but for last 2 years been trying to figure out my fuel gauge flicker? I don't seem to find anything on answers to this has anyone figured out what there's was? Can anyone be more specific or help me out on where to start besides dropping the gas tank! I hope it doesn't come to this!

they all have this fuel guage problem ..ya its the fuelpump sender assy. ya you have to remove the fuel pump and replace.. I have had this for 7 years now. 2000 silverado. when the pump dies it will be fixed. new pump is expensive.

a thump when in drive stoped and then when accellerating the thump is felt this is the drive shaft yoke could be bad or the transfercase fluid needs replacing. with 4wd the transfercase fluid needs regular replacing and this is when it causes this issue..later year models had bad yokes.[soft].

[Cholo Mike]

Originally Posted by j cAT

they all have this fuel guage problem ..ya its the fuelpump sender assy. ya you have to remove the fuel pump and replace.. I have had this for 7 years now. 2000 silverado. when the pump dies it will be fixed. new pump is expensive.

a thump when in drive stoped and then when accellerating the thump is felt this is the drive shaft yoke could be bad or the transfercase fluid needs replacing. with 4wd the transfercase fluid needs regular replacing and this is when it causes this issue..later year models had bad yokes.[soft].

I had my fuel pump replaced by Chevy dealer and still the same problem is this unit one or separate. it came with a lifetime warranty so should i take it back unless its a separate piece?

[j cAT]

Originally Posted by Cholo Mike

I had my fuel pump replaced by Chevy dealer and still the same problem is this unit one or separate. it came with a lifetime warranty so should i take it back unless its a separate piece?

the fuel pump if OEM GM/AC DELCO isw all in one ...

just to be sure of your problem ..............is this high frequency vibs or a needle that wanders from full to empty......

[Cholo Mike]

Originally Posted by j cAT

the fuel pump if OEM GM/AC DELCO isw all in one ...

just to be sure of your problem ..............is this high frequency vibs or a needle that wanders from full to empty......

fast and high vibration in place not from full to empty just in place. but sometimes i get scared its a false reading

[j cAT]

Originally Posted by Cholo Mike

fast and high vibration in place not from full to empty just in place. but sometimes i get scared its a false reading

this vibs problem is a hard one to find. I believe it is in the dash panel circuitry. I am not 100% on that. see if you can find more info about this issue and indicate its the high frequency needle vibration problem not the wandering guage needle issue.

post back how it was corrected and if possible what exactly failed to cause this.

the GM circuits that control this , are top secret so how this all comes about is very difficult.

the gm dealerships do not have any knowledge about those circuits. internet dash repair providers do.

[1996ctnc]

I got given to me a 99 k3500 LS from my brother. He put 6000+ into it and after I got it I am having problems with the fuel guage "wiggin'" out. It would move back and forth then for a few days it stopped read 1/2 tank. My wife and I were going to pick up our daughters from a friends house didn't even make it 2 blocks and yup it RAN OUT OF GAS. Now it is doing the vib.

[j cAT]

Originally Posted by 1996ctnc

I got given to me a 99 k3500 LS from my brother. He put 6000+ into it and after I got it I am having problems with the fuel guage "wiggin'" out. It would move back and forth then for a few days it stopped read 1/2 tank. My wife and I were going to pick up our daughters from a friends house didn't even make it 2 blocks and yup it RAN OUT OF GAS. Now it is doing the vib.

post #13 is what your problem is all about.

use the trip odometer and avoid running outof fuel. if this continues the fuel system will fail.