gas gauge issues

[bug8688]

I have an 84 Custom Deluxe with a 305 and an 18 gallon tank. I'm haviing a few issues with my gas gauge. Problem #1 - Every time I fill up it reads almost a little over an eight over full. Problem #2 - The reading is very unstable it has fluxuated with a difference of up to a quarter tank change just going across the street to the gas station from work. Like I leave work with a quarter tank and get to the gas station with a half tank. Or while driving it may dip down some then come back up. I normally don't let it read below half but still kinda worried bout getting stranded during the times when gas prices are high and funds are low. Does anyone have any ideas?

[81_Chevy]

same probelms with mine, its normal because there is no baffles in the gas tank to stop the gas from moving back and fourth in the tank. the 1/8 over is normal as well, does it on all 3 of my chevys.

[Captkaos]

It actually has nothing to do with the lack of baffles and more to do with the anglularity of the gauge sweep.  Newer vehicles have a linear sending unit.

[bug8688]

So its all normal then? I thought I might have a wiring issue.

[zieg85]

Not that this helps your question however they had 16 or 20 gallons tanks in stock capacities

[bug8688]

Ok then I must have the twenty cuz from running on fumes filling it took 18 gallons. But the reason I was wondering what could cause the issue is I have to replace my fuel tanks staps and was wondering if it might be something I could fix or replace while the tank is out anyway.

[Captkaos]

Certain fluctuations are to be expected, but the gauge should be in range 97% of the time.