Gas gauge acting up?

[setty7]

My gas guage is starting to bounce around. does anyone know what this is and how much it would be to fix? Lik if I am at half tank when I start the truck up it goes all the way to full then back down. After I start it up and it sits on how much fuel is left it will vibrate. I have a 99 tahoe obs. Thanks for yalls help!

Justin

 

[SunlitComet]

vibration is usually the gauge itself. If you disconnect the the sender from the pcm how does it the gauge react?

 

[LI99HOE]

My gas guage is starting to bounce around. does anyone know what this is and how much it would be to fix? Lik if I am at half tank when I start the truck up it goes all the way to full then back down. After I start it up and it sits on how much fuel is left it will vibrate. I have a 99 tahoe obs. Thanks for yalls help!

Justin

I had the same problem happen with my Tahoe today...actually the guage was shaking for a couple of weeks, but worked.

@ Sun.... is the 2 wire plug @ the back of the tank(I think purple, and maybe brn+purple?) that just disconnects? Whats the easiest<<key word, way to break the circuit, and narrow down the culprit?

 

[SunlitComet]

Should have more then two wires but yes it just disconnects use that to isolate and measure sender resistance or to isolate chassis wire to cluster connector to check for shorts or opens.

 

[LI99HOE]

Awesome....thanx Sun.

Update-- I disconnected the 2 wire plug, and did a resistance test. I'm getting ~4 ohms.
Right now I have 3/4 of a tank
What should the empty/full resistance readings be?
I've heard 40 ohms full/250 ohms empty
and 90 ohms full/0 ohms empty <<<< which is correct??

 

[Sp1nn3y]

At first i was like, Yay someone asked a question that i have as well.. but then it went to a different language so quick.. If i wanted to bring the truck in to check said problem, howmuch would they usually charge?

goin up/down hills, even smaller ones fluctuates the meter..

 

[LI99HOE]

At first i was like, Yay someone asked a question that i have as well.. but then it went to a different language so quick.. If i wanted to bring the truck in to check said problem, howmuch would they usually charge?

goin up/down hills, even smaller ones fluctuates the meter..

LOL SP1--- I'm an electronic/mechanical tech so I went tech on this one.

Around me every shop has different "checkout" fees, hopefully you have a honest/reliable/reasonable shop around you. I would call around.
I have read about a dampening upgrade to reduce the small fluctuations in the fuel gauge while driving, but I am not sure of the part#.
Sun might be right.... a vibrating needle could be the gauge itself, but unless you can pull things apart, and measure things yourself, your gonna need a tech.

OK, I took a 47 ohm resistor, and jumped the two wire terminal @ the tank..... no difference in the gauge....still vibrates and reads inaccurately. I'm pretty sure the gauge itself is the culprit.
I ordered a used cluster from ebay, when it comes in I'll know for sure.
Bummer I'm prob. going to have to remove my custom cluster overlays to change it if it's bad....hopefully they don't get damaged so I can re-install them.

 

[JcKinney]

My '95 has a floating gauge. When you stop, it heads towards full, then levels off. At takeoff it heads to the E and then levels off again.

 

[96GMCYukonGT]

mine did this too and then i changed my tank cause it was leaking and changed my feul sending unit and its fixed now so your fuel sending units probably dicked

 

[LI99HOE]

My '95 has a floating gauge. When you stop, it heads towards full, then levels off. At takeoff it heads to the E and then levels off again.

I heard sumthin' about a plastic clip that breaks allowing the arm to float easily, giving that exact symptom. Not sure, but I think the sending unit needs to be changed. If so,
might as well get the one with a new pump, harness, and gasket.
Job done did right.