: 75 Gas Guage



75sled
07-14-09, 04:38 PM
Hey does anyone know what makes the gas guage move fluid like rather than being real jerky. When i first got the car it moved up at down like it was supposed to, but now it is really jerky and indicates every little movenment that the bobber in the tank has. Not sure what happened.

05devilledave
07-15-09, 02:02 AM
Your fuel gauge is faulty. there is a bi-metallic strip in the gauge that is heated depending on how much current it recieves from the sender in the fuel tank. Bi-metalic is 2 pieces of metal laminated together, and they expand and contract at different rates, causing a fluid motion. If on of the plates is cracked or broken. You will get a jerky instant motion from the only remaining metallic strip left because it no longer has the other strip to balance the movement. Time for a new fuel guage

75sled
07-15-09, 08:38 AM
Sorta figured. That looks like it is a pain to swap. I haven't read the FSM yet, but i have seen some dashes taken apart at the junk yard and that don't look too fun.

Caddy75
07-15-09, 03:57 PM
When you say jerky is that the same as the needle moving around when you go round a corner? I thought that would just be the fule getting sloshed around within the tank.

05devilledave
07-15-09, 04:38 PM
Everyones car sloshes around fuel when you go around a corner, the thing is, you should not be able to see that in your fuel guage. They designed the guages to have a slow response time so that you dont have to watch the guage jerk back and forth like crazy every time you hit a bump.

Maverick87
09-27-09, 05:05 PM
I'm not the foremost expert on fuel gauges, so this is just my 2 cents.
I drove my '75 Coupe home over 75 miles when I bought it with a stuck gauge. I had a '93 Sedan with the same problem before and hit the top of the dash with an open hand and it freed the gauge, no problems since.

:bouncy:

75sled
09-29-09, 09:54 AM
That is another problem that i have with mine. From time to time i will have to RAP the top of the dash over the gauge to make it work. But even then it jumps around with each and every movement of the gas inside the tank. It didn't do this when i first got the car. It was very smooth to rise each time and you never saw the movement. It would just slowly and gradually move towards the "E".

caddeville89
09-30-09, 01:08 PM
"It would just slowly and gradually move towards the "E"."

I always like to think the slower the better in this situation.

75sled
09-30-09, 01:31 PM
^^^AMEN TO THAT!!! Most of the time not so much slow as gradual