Hi all,

My dad and I just got a 1970 El Camino SS 396. I noticed when I drive it and go from reverse to drive, or stop suddenly, the gas gauge starts to jump about 1/4 tank on the gauge. Is there a problem with the sending unit or is it due to the fact that the gas in the tank is sloshing back and forth causing the sending unit float to go up and down quite rapidly?

Aside from this problem, the gauge reads fairly accurate. The truck has 43,000 original miles on it and the car is all factory original and the car is in immaculate shape.

Any help would be greatly appreciated.

These beasts have wide flat gas tanks. My 77SS does the same thing. It's just slosh. :roll:

Keep the tank full as much as possible, should help stop the gas from sloushing around, besides with a 396 you'll need a full tank! :lol:

while you may not remember it, your dad probably does. back then (i have a 71 454) GM and probably everyone else, used tank floats. as the name implies, the sending unit floats on the liquid level. depending on whether it floats from the left or from the right, your gauge could actually dip below empty when you make a hard turn not to mention a quick start or hard stop as you detail. it's just the nature of the beast, and most of us have been spoiled by getting fairly accurate, non-floating readings from our guages thanks to electronic sensors that have replaced the old float method. you'll also notice that thanks to the way the float method works, it seems that it takes a whole lot longer to go from full to 1/2 a tank than it does to go from 1/2 to empty.