Hello all,

My beloved car has sat for quite some time, as chapters of life closed and even more opened. I've since rekindled my passion for my car, and have begun to clean her up and hope to take her out soon.

When I fired the car up last night, it started without issue (I'm sure my new optima battery helped) - this was good news. What is troubling is that now my fuel gauge is not reading accurately - bobbing all over the place (I know it has a full tank). Also, my temp gauge does not work at all.

I've done a little research, and have seen mixed guidance on the fuel issue - could it be what some of you call the floater? It sounds like it's not the easiest fix. What can cause the gauge to do this?

The temp gauge I'm also lost on - it's a carbed 305, so my thoughts are that there is some sensor in or around the engine/carb that regulates this. If I locate it, how can I test if it's a bad wire/sensor?

Any help would be greatly appreciated - the car seems to run fine with these issues (although I think my valve seals are bad).

 

I would worry about the fuel gauge not working. My Trans Am has been sitting for almost seven years and like you I have decided to clean her up with hopes of finishing something I started years ago. I kept starting my up everyday and kept putting gas in the tank and I supposed the float broke free and the gauge started working again.

 

The temp switch for the gauge is usually located on the driver side cylinder head. In my case (83 bird) the wire is green. If you ground the wire the gauge should read at it's max. The temp switch is a variable resister, which means it varies it's resistant to ground based on temp. Colder ( more resistance ) makes the gauge read lower, less resistance ( hotter ) the gauge goes higher. an OHM meter connected to the switch would tell you if it is working or not based on the resistance reading as the temp of the engine changes. Grounding the wire will tell you if the gauge is functioning at all.

First thing I would do is unplug and plug in the connector to the temp switch a few times. Very likely this has become tarnished from sitting and is no longer making connection.

Gauges get dirty, and your floating fuel gauge my have some gunk inside causing it to act funny. Sending units in the tank don't usually cause a jumpy gauge, usually they will read low, indicating a float problem or a dead spot in the rheostat which the float arm is attached too. If the problem is in the rheostat causing the jumpy gauge than it might be some corrosion that built up from sitting with old moisture gathered watered-down gas. May clear itself up. There is no way to know if its the gauge in this case or the wires to the sending unit, or the sending unit itself without swapping gauges, and tracing wires out. Doubt it's a bad wire though. Could also be a bad connection to the cluster itself where the harness plugs into the back. Might be slightly out or just dirty. Too many possibilities, just have to knock em out one at a time till you eliminate everything easy to check and are left with the sending unit in the tank.

Personally, I think it is the gauge. GM fuel gauges are known for been kinda funny, and with age, some get REALLY funny. Run the tank down to near empty - and fill it up to the max. Doing this a few times will work that gauge through its whole sweep ( and the sending unit ) which may clear up any tarnish/corrosion/dirt that has built up inside of it. If not, tear out the cluster and remove the gauge itself, get some good electrical cleaner ( do not use brake/carb or throttle cleaner as these could ruin the internals and plastics inside the gauge ) and spray that motha' out.

Good hunting!