Fuel Gauge going screwy

[budget_crx]

So my buick's gauge is jumping all over the place, usually going well past the FULL marker. When the car is sitting and idling it reads as normal, but when the engine revs or i start moving the needle goes all over the place. Its not even related to the amount of throttle im giving it (like if i accelerated it would move more). what could be causing this? is my float messed up or something?

 

[SS_Sean]

Sounds like a short in the system. Check all the wiring from the sending unit in the tank to the dash. Trust me, the dash is NO fun pulling apart. I am fighting demons, as well.

 

[budget_crx]

My turn signals stopped working today as well but i thought it was just a bad relay. Turns out my brake lights are not working properly as well, sometimes the driver light doesnt work, sometimes the passenger doesnt. Im thinking with all of this happening recently a ground has loosened or corroded, could this be the problem? a ground stretcher kit might be a good idea anyway though...

 

[Blown&Injected]

I cleaned the sender in the tank with an eraser and it had my gauge reading right - then it failed just like yours seems to be going. The part that sends the signal is fradgile and I believe I damaged it

I also had some screwie light/turn signal issues and it was just due to a corroded lamp socket and bad ground wire, I think it was near the battery.

Sounds like some of the types of things one may expect with a 20+ year old car

 

[garyk1970]

also sheck a ground in the truck which is common ground for light/fuel pump/sender gage.inside trunk,drivers side floor near tail lamps assembly.

 

[budget_crx]

thanks for the info guys, ill check out those grounds and see where that gets me!

 

[johnnyttype]

had same exact problem as u, needle liked to jump everywhere when i braked, accelerated or on some occasions sat still! eventually it got to the point that the needle would play hide-n-go-seek with me below the dash bezel for the whole car ride!!! pulled sending unit, found little fingers that ride along the fuel level sensor portion of the sender to be worn down and the bridge that the fingers rode on, if i remember correctly, was warped or something...it didnt look right is best way i can put it hth

 

[Jerryl]

I installed the correct replacement hanger 0-90 ohm. Full tank doen to 10 gal, the gage reads about 3/8.

Disconnected the sending unit at the tank (pump/sending unit connector) and it reads past full. It reads empty when the wire to the main is grounded. Ground is good,

So . . . . . I proceed in measuring the voltage. It is about 7.2V at both the connector and the pink wire in the trunk. (I think this is the issue)
Anyone run across this before?

 

[Gentry1]

Gauge trouble

Your problem is your fuel sender. These gauges never die - we actually have to talk people out of sending them to us. The gauge is getting voltage and it does work, as indicated by you grounding the sender wire and the gauge going to "E". The gauge is a 0-90ohm unit and when you ground it the gauge should go to "E" as it does.
You can verify the sender problem by filling the tank with fuel and connecting an ohmmeter to the sender - does 90ohms, give or take, come out of the sender? I doubt it does.
Half tank should send somewhere around 45 ohms.
Don't take your dash apart.

I hope this helps,
Gentry
AutoInstruments Corp.
Collinsville, VA

 

[Jerryl]

So . . . . . I proceed in measuring the voltage. It is about 7.2V at both the connector and the pink wire in the trunk. (I think this is the issue)
Anyone run across this before?

Your problem is your fuel sender. These gauges never die - we actually have to talk people out of sending them to us. The gauge is getting voltage and it does work, as indicated by you grounding the sender wire and the gauge going to "E". The gauge is a 0-90ohm unit and when you ground it the gauge should go to "E" as it does.
You can verify the sender problem by filling the tank with fuel and connecting an ohmmeter to the sender - does 90ohms, give or take, come out of the sender? I doubt it does.
Half tank should send somewhere around 45 ohms.
Don't take your dash apart.

I hope this helps,
Gentry
AutoInstruments Corp.
Collinsville, VA

Gentry,
Thanks for the reply.
Do you know what the voltage should be?
I am Ass-U-M-ing 12V