Jumpy fuel gauge

[Bonnewagon]

I have an old GM fuel gauge that jumps around and flits back and forth as if it's reacting to every ripple in the gas tank. I know there is a dampening mechanism in the gauge to slow it down and stop that behavior. What I can't find out is what exactly that mechanism is so I can repair it. I have another crummy one to dissect if need be, but I am hoping someone knows the answer before I perform exploratory surgery.

 

[pontiacgp]

your sure it's not a loose ground?

 

[Bonnewagon]

Yeah, cause' when I shove or rock the car, the needle flips back and forth as if following the gas sloshing. Plus I tested it with the fugly spare I have. Of course the fugly one works perfectly.....

 

[pontiacgp]

what do they use for the resistance on the arm?

 

[Bonnewagon]

My 68' Pontiac Diagnosis Manual quotes -"The dash unit is an electromagnetic instrument consisting of a permanent magnetic armature and spindle assembly mounted in a pocket in center of a plastic core with a quantity of silicone dampening fluid to restrict pointer movement due to car motion". So you would think it would leak out and stain everything, but it's clean as a whistle. The face of the gauge is riveted on, but I can defeat them easily enough. It's more dicey removing the pointer without ruining it. If I could do that I would disassemble both and use the guts from the fugly one with the face of the pretty one.

 

[Peter]

my fuel gauge does the same thing, i always assumed it was a resister or something in the fuel pump sending unit but i honestly have no idea cuz i have always ignored it

 

[pontiacgp]

I've never looked at one but it sounds like the it's a sealed unit with the silicone stuck in the middle. I agree that if the silicone leaked there should be some residue..

 

[Bonnewagon]

Internet search is useless. The guys who repair these are keeping quiet about it. This is a case where I will try and find a broken one and smash it just to see what makes it tick.

 

[pontiacgp]

:|

 

[skatepirate77]

Hey Bonnewagon, Don't know if this will apply to you but read the last post on here http://www.montecarloss.com/community/u ... ber=715392. It talks about clips on the back of the cluster that can cause false gauge readings. I hope this can help you out.