Hi Everyone

On my gas guage when I turn off key is the needle supposed to stay where it was with key on or go down to empty. Just had my Cutlass a few months,thanks for inputs in advance.

 

The needle could go anywhere when the key is off. It means nothing as there is no current flow. It's where it goes when the key is on that matters. Does your gauge work correctly otherwise? If so, don't give it another thought.

 

Mine stays about where it was while energized. It's not like new cars that show empty when turned off. I guess they did that to discourage gas thieves from knowing how much fuel was left in the tank...

 

X3, there is no park position for the gauge when it loses power.

 

Thanks Guys

When full with gas the guage goes above full to about 1/2 way to the hot idiot light
thanks

 

But the point is, it does move correctly with the amount of fuel in the tank?

The gauge on my '73 wagon does the same thing. It's offset one hashmark to the right. When full, the needle goes past the F about the same distance as between the 3/4 and Full marks. When nearly empty, it's at about the 1/4 mark. But it otherwise works fine, and I can live with this.

The needle, by the way, parks itself anywhere when the ignition is off, usually somewhere in the mid-gauge range. But it moves to the correct position when the engine is started.

 

That's completely normal.

 

Thank you all for the responses about my gas guage,sounds like my gas guage works like the rest of the 40 plus year old guages.

 

Don't assume it works this way because it's old. It might very well have worked this way when it rolled off the assembly line. Gas gauge systems of that era were not precision instruments.

 

Mine wobbles all over the place as I drive. It settles after I stop, and it's been accurate so far. But it never worked until we dropped the tank and reconnected it.

 

This pretty much goes without saying. Few things work if they're not connected.

 

I know with mine, it really starts to fluctuate while driving when it gets below a 1/2. As long as it's moving around I know I have gas. I usually fill it when it gets around 1/2 tank.

 

Not surprising, really. The less gas is in there, the more sloshing around it does when you go around corners and over bumps.

 

Now that I've got my Super 88 on the road, it's time to tackle the fuel gauge. I originally thought I had a typical ground problem since the needle pins at full with the ignition on. However, the needle goes to empty when I put it in reverse, and back to full when I put in any other position and so now I'm confused. Wish me luck, I'm going in.....

 

When I had the wire to my sending unit unhooked on my 71 Cutlass I turned on the key and noticed the needle was way past full and over towards the hot light as you mentioned- just about horizontal. So I assume that's where it goes when it's open. When it was reconnected it worked fine. Later on I noticed the gas gauge in my Vista went to the same horizontal position, then went back to being ok. I assume there is a intermittent open or loose connection? Sounds like that maybe what you have also. I wonder if there was a bad spot in the rheostat would it cause that to happen only when the float was in that position?

 

The first part of the problem does sound like a ground problem, and I'll bet the second one is also a ground problem. Bad or partially bad grounds cause electricity to flow in ways never intended. With the ignition ON, the gauge, if working properly, should register the amount of fuel in the tank regardless of what position the gear selector is in. Since it goes to Full, I would work with that and look for a bad connection where the sending unit ground wire attaches or an open in the wire between the dash gauge and the sending unit.

The standard test is to disconnect the wire coming from the gauge at or near the sending unit (there is usually a connector in the license plate area that you can pull apart) and ground the side coming from the gauge. If the gauge goes to E when grounded with the ignition on and then goes past F when you remove the wire from ground, the dash gauge and the wire from it to the rear of the car are fine, and your problem is at the sending unit end (bad sending unit, bad connection to sending unit, bad ground). Otherwise, the problem is between the sending unit and the gauge.

 

Yes, but exactly where it goes when it goes past F is not important. Just that it goes to F or past it when the circuit is open. Remember, the gauge is just a 90-ohm variable resistor calibrated so that zero Ohms is E and 90 Ohms is F. Since an open circuit is infinite resistance, which is much more than 90, the gauge/Ohmmeter reads past F.

Yes, this is what it sounds like.

It could be this, too, but it's important to do the tests in the correct order. You want to do the tests to rule out all external possibilities (bad grounds, open or intermittent connections) before going through the major hassle of dropping the tank to get at the sending unit. In other words, you want to make sure the problem really IS the sending unit before going after it.

 

My car has that intermittent way past full thing. I can pull on the sending unit wire behind the license plate and the gauge reads correctly, so I am thinking it is a loose connection to the sending unit. I had a similar issue on my '70 where the wire has a push-on terminal that slips onto a stud on the sending unit, and the terminal was slightly lose. I crimped it a bit with pliers to tighten it and never had that issue again. I'm just too lazy to drop the tank on the '71 to do that.