The Stovebolt Site Forums The Shop Area The Electrical Bay gas gauge bounce

Dose anyone have a gas gauge that bounces with movement of the truck. I am a 47 6v stock all the way and just noticed yesterday that my guage is bouncing all over the place when the tank is about 1/3 full. When I stop, it settles down and registers correctly. Implies the float is moving fairly easily seems like. I wouldn't think this presents any problem and doesnt have a fix, guess I am just wondering..I do that more and more as I get older..

Sure seems like that is the problem, or a ground is loose? Don't know how it would be fixed either though.

My '37 does the same thing. I even bought a NOS fuel gauge thinking my was to loose, the new one is just like the old one. My fuel sender is also new from a local street rod shop (modern design). I have been tempted to try some heavy oil on the needle but can't get myself to do it yet. Joe

There are baffles in the tanks to help minimize the sloshing & associated excess gauge movement. At just 1/3 tank you won't get much benefit from the baffles. These old gauges work in real time unlike modern gauges. I would guess that what you are seeing is normal for your truck.

I like the logic here. All the wires are tight and so I think it is the lack of baffle action on a low amount of fuel. Appreciate the insight

I believe the above answers are correct as to the cause of the problem. I would not add a grease or heavy oil to your movement unless you are very good at working on gauges. On the other hand, there may be an electrical solution to the problem. I have not tried this but if one were to put a capacitor across the gauge from power input lead to ground could it dampen the voltage swing or slow down the needle movement? Or maybe put the capicator in parallel with the sender, that would make a RC circuit and dampen the voltage drop across the sender. Some of the guys, like Atomarc, that are more familiar with fuel gauges might comment on this. It's just an idea.

BeltFed has the solution.

All modern vehicles run this same fix for the same reason.

Notice how your daily driver takes some time to register on start-up, and after filling the tank?

The capacitor acts as a shock absorber, taking in the highs and lows of the sender and levelling it all out to a nice stable signal.

A real cheap fix too!

Just a normal capacitor like in the distributor? I will give it a try. Joe

I would think an electrolytic type capacitor would be the right kind. I don't have any idea as to the valve. I believe the distributer capacitor is of the electrolytic type, so give it a try. You may have to go bigger in value such as a you would find in a old tube radio power supply. Good luck and let us know how it works for future sufferers of this problem. BTW, these tpyes of capacitors are polarity sensitive. The case is usually negative or ground.